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Sample records for 2h-chromene ring system

  1. A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

    PubMed Central

    Mikhalchenko, Oksana S; Korchagina, Dina V; Salakhutdinov, Nariman F

    2016-01-01

    Summary Conditions enabling the single-step preparative synthesis of chiral 4-fluoropolyhydro-2H-chromenes in good yields through a reaction between monoterpenoid alcohols with para-menthane skeleton and aldehydes were developed for the first time. The BF3·Et2O/H2O system is used both as a catalyst and as a fluorine source. The reaction can involve aliphatic aldehydes as well as aromatic aldehydes containing various acceptor and donor substituents. 4-Hydroxyhexahydro-2H-chromenes were demonstrated to be capable of converting to 4-fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration. PMID:27340456

  2. Crystal structure of (6-bromo-2-oxo-2H-chromen-4-yl)methyl morpholine-4-carbodi­thio­ate

    PubMed Central

    Kumar, K. Mahesh; Roopashree, K. R.; Vinduvahini, M.; Kotresh, O.; Devarajegowda, H. C.

    2015-01-01

    In the title compound, C15H14BrNO3S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.034 (2) Å, and the morpholine ring adopts a chair conformation. The dihedral angle between best plane through the 2H-chromene ring system and the morpholine ring is 86.32 (9)°. Intra­molecular C—H⋯S hydrogen bonds are observed. In the crystal, inversion-related C—H⋯S and C—H⋯O inter­actions generate R 2 2(10) and R 2 2(8) rings patterns, respectively. In addition, the crystal packing features π–π inter­actions between fused benzene rings [centroid–centroid distance = 3.7558 (12) Å]. PMID:26279923

  3. Bi(OTf)3-catalyzed addition of isocyanides to 2H-chromene acetals: an efficient pathway for accessing 2-carboxamide-2H-chromenes.

    PubMed

    Lyu, Longyun; Jin, Ming Yu; He, Qijie; Xie, Han; Bian, Zhaoxiang; Wang, Jun

    2016-09-14

    Bismuth triflate (Bi(OTf)3) is identified as an efficient catalyst for the direct addition of isocyanides to 2H-chromene acetals. The large scope of isocyanides and chromene acetals makes them suitable substrates in this catalytic system. By this synthetic strategy, a polyfunctional molecular scaffold, 2-carboxamide-2H-chromenes could be prepared efficiently in one step up to 95% yield. In addition, this efficient and practical protocol proceeded smoothly in the gram scale even when the catalytic loading was reduced to 2 mol%. PMID:27503764

  4. Crystal structure of (7-methyl-2-oxo-2H-chromen-4-yl)methyl piperidine-1-carbo­di­thio­ate

    PubMed Central

    Roopashree, K. R.; Meenakshi, T. G.; Kumar, K. Mahesh; Kotresh, O.; Devarajegowda, H. C.

    2015-01-01

    In the title compound, C17H19NO2S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.0383 (28) Å, and the piperidine ring adopts a chair conformation. The 2H-chromene ring makes dihedral angles of 32.89 (16) and 67.33 (8)°, respectively, with the mean planes of the piperidine ring and the carbodi­thio­ate group. In the crystal, C—H⋯O and weak C—H⋯S hydrogen bonds link the mol­ecules into chains along [001]. The crystal structure also features C—H⋯π and π–π inter­actions, with a centroid–centroid distance of 3.7097 (17) Å. PMID:26396821

  5. Crystal structure of (7-chloro-2-oxo-2H-chromen-4-yl)methyl N,N-di­methyl­carbamodi­thio­ate

    PubMed Central

    Kavitha, H. D.; Vinduvahini, M.; Mahabhaleshwaraiah, N. M.; Kotresh, O.; Devarajegowda, H. C.

    2015-01-01

    In the title compound, C13H12Cl N O2S2, the 2H-chromene ring system is almost planar, with a maximum deviation of 0.005 (2) Å. The packing features C—H⋯S hydrogen bonds and π–π inter­actions between fused benzene rings of chromene [shortest centroid–centroid distances = 3.6553 (13) and 3.5551 (13) Å]. PMID:26029447

  6. Crystal structure of 2-oxo-N′-phenyl-2H-chromene-3-carbohydrazide

    PubMed Central

    Mague, Joel T.; Mohamed, Shaaban K.; Akkurt, Mehmet; Younes, Sabry H. H.; Albayati, Mustafa R.

    2015-01-01

    In the title compound, C16H12N2O3, the 2H-chromene moiety is essentially planar, with an r.m.s. deviation of the nine constituent atoms from the mean plane of 0.0093 Å, and makes a dihedral angle of 76.84 (3)° with the pendant phenyl ring. An intra­molecular N—H⋯O hydrogen bond helps to determine the conformation of the side chain. In the crystal, N—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules, forming [100] chains. PMID:26870466

  7. Polymorphism in 3-acetyl-4-hydroxy-2H-chromen-2-one.

    PubMed

    Ghouili, Afef; Brahmia, Ameni; Ben Hassen, Rached

    2015-10-01

    A new polymorph (denoted polymorph II) of 3-acetyl-4-hydroxy-2H-chromen-2-one, C11H8O4, was obtained unexpectedly during an attempt to recrystallize the compound from salt-melted ice, and the structure is compared with that of the original polymorph (denoted polymorph I) [Lyssenko & Antipin (2001). Russ. Chem. Bull. 50, 418-431]. Strong intramolecular O-H...O hydrogen bonds are observed equally in the two polymorphs [O...O = 2.4263 (13) Å in polymorph II and 2.442 (1) Å in polymorph I], with a slight delocalization of the hydroxy H atom towards the ketonic O atom in polymorph II [H...O = 1.32 (2) Å in polymorph II and 1.45 (3) Å in polymorph I]. In both crystal structures, the packing of the molecules is dominated and stabilized by weak intermolecular C-H...O hydrogen bonds. Additional π-π stacking interactions between the keto-enol hydrogen-bonded rings stabilize polymorph I [the centres are separated by 3.28 (1) Å], while polymorph II is stabilized by interactions between α-pyrone rings, which are parallel to one another and separated by 3.670 (5) Å. PMID:26422214

  8. Ecocatalysis for 2H-chromenes synthesis: an integrated approach for phytomanagement of polluted ecosystems.

    PubMed

    Escande, Vincent; Velati, Alicia; Grison, Claude

    2015-04-01

    A direct, general and efficient method to synthesize 2H-chromenes (2H-benzo[b]pyrans), identified as environmentally friendly pesticides, has been developed. This approach lays on the new concept of ecocatalysis, which involves the use of biomass from phytoextraction processes, as a valuable source of metallic elements for chemical synthesis. This methodology is similar or superior to known methods, affording 2H-chromenes with good to excellent yields (60-98%), including the preparation of precocene I, a natural insect growth regulator, with 91% yield. The approach is ideal for poor reactive substrates such as phenol or naphthol, classically transformed into 2H-chromenes by methodologies associated with environmental issues. These results illustrate the interest of combining phytoextraction and green synthesis of natural insecticides. PMID:25131683

  9. Crystal structure of 4-azido­methyl-6-isopropyl-2H-chromen-2-one

    PubMed Central

    Krishnamurthy, M. S.; Begum, Noor Shahina; Shamala, D.; Shivashankar, K.

    2015-01-01

    In the title mol­ecule, C13H13N3O2, the benzo­pyran ring system is essentially planar, with a maximum deviation of 0.017 (1) Å. In the crystal, weak C—H⋯O hydrogen bonds link mol­ecules into ladders along [010]. In addition, π–π inter­actions between inversion-related mol­ecules, with centroid–centroid distances in the range 3.679 (2)–3.876 (2) Å, complete a two-dimensional network parallel to (001). PMID:26029427

  10. In situ direct photoproduction of ketenes from substituted coumarins isolated in solid argon: The case of N-(2-oxo-2 H-chromen-3-yl)acetamide

    NASA Astrophysics Data System (ADS)

    Kuş, N.; Breda, S.; Fausto, R.

    2009-04-01

    In this study, the infrared spectrum of N-(2-oxo-2 H-chromen-3-yl)acetamide (3-acetamidocoumarin; 3AC) isolated in solid argon, at 10 K, was obtained and assigned. In consonance with the relative energies of the three conformers predicted theoretically, only the most stable form was observed experimentally. This conformer is stabilized by two intramolecular hydrogen bonds and is similar to the structural unit of 3AC found in crystalline phase. Upon in situ UV ( λ > 215 nm) irradiation of the matrix-isolated compound, the characteristic IR intense band due to the antisymmetric stretching vibration of the ketene ( sbnd C dbnd C dbnd O) group was observed, indicating occurrence of the ring-opening isomerization reaction to the open-ring ketene isomeric of 3AC. In consonance with the theoretical structural predictions for the most stable isomers of this photoproduct, the experimental data indicates that it is produced in the E arrangement of the (O dbnd )C sbnd C dbnd C sbnd C( dbnd C dbnd O) fragment. There were also experimental indications pointing to occurrence of a second photoreaction channel, corresponding to decarbonylation. On the other hand, contrarily to what is generally observed for α-pyrones derivatives, including unsubstituted coumarin, no photochemical production of Dewar isomer of 3AC was observed. This last result, follows the trend observed for 2-pyrone-3-carboxylate, and seems to be a quite general rule for matrix-isolated α-pyrones bearing relatively volumous substituents at the position 3, as a consequence of the unfavorable relaxation of the matrix around the guest molecule that would be required to accommodate the Dewar isomers of these compounds, whose structure deviates strongly from planarity, thus mismatching the primarily occupied matrix sites.

  11. Crystal structure of 4-methyl-7-prop-oxy-2H-chromen-2-one.

    PubMed

    Estrada-Soto, Samuel; Sánchez-Recillas, Amanda; Navarrete-Vázquez, Gabriel; Tlahuext, Hugo

    2014-11-01

    The asymmetric unit of the title compound, C13H14O3, contains two independent mol-ecules, A and B, that are inter-connected through an offset π-π inter-action [inter-centroid separation = 3.6087 (4) Å]. The fused benzene and pyran-2-one rings in each mol-ecule are essentially coplanar, having dihedral angles of 1.22 (12) and 1.57 (12)° for mol-ecules A and B, respectively. Similarly, the coumarin ring system and the 7-prop-oxy substituent are close to being coplanar [C-C-O-C torsion angles = 2.9 (2) and 1.4 (2)° for mol-ecules A and B, respectively]. In the crystal, the mol-ecules are connected by C-H⋯O hydrogen bonds, forming supra-molecular tapes along [100] that are linked into a three-dimensional network by C-H⋯π inter-actions, as well as by the aforementioned π-π inter-actions. PMID:25484772

  12. Computational and spectral studies of 6-phenylazo-3-(p-tolyl)-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Manimekalai, A.; Vijayalakshmi, N.

    2015-02-01

    6-Phenylazo-3-(p-tolyl)-2H-chromen-2-one 4 was prepared and characterized by IR, 1H, and 13C NMR spectral studies. The optimized structure of the chromen-2-one 4 was investigated by the Gaussian 03 B3LYP density functional method calculations at 6-31G(d,p) basis set. The gauge-independent atomic orbital (GIAO) 13C and 1H chemical shift calculations for the synthesized chromen-2-one in CDCl3 were also made by the same method. The computed IR frequencies of the chromen-2-one and the corresponding vibrational assignments were analyzed by means of potential energy distribution (PED%) calculation using vibrational energy distribution analysis (VEDA) program. The first order hyperpolarizability (βtot), polarizability (α) and dipole moment (μ) were calculated using 6-311G(d,p) basis set and the nonlinear optical (NLO) properties are also addressed theoretically. Stability of the chromen-2-one 4 molecule has been analyzed by calculating the intramolecular charge transfer using natural bond order (NBO) analysis. The molecular electrostatic potentials, HOMO-LUMO energy gap and geometrical parameters were also computed. Topological properties of the electronic charge density in chromen-2-one 4 were analyzed employing the Bader's Atoms in Molecule (AIM) theory which indicated the presence of intramolecular hydrogen bond in the molecule.

  13. Novel 2H-chromen-2-one derivatives of resveratrol: Design, synthesis, modeling and use as human monoamine oxidase inhibitors.

    PubMed

    Ruan, Ban-Feng; Cheng, Hui-Jie; Ren, Jing; Li, Hong-Lin; Guo, Lu-Lu; Zhang, Xing-Xing; Liao, Chenzhong

    2015-10-20

    Using a fragment-based drug design strategy, two biomedical interesting fragments, resveratrol and coumarin were linked to design a series of novel human monoamine oxidase (hMAO) inhibitors with a scaffold of 3-((E)-3-(2-((E)-styryl)phenyl)acryloyl)-2H-chromen-2-one, which demonstrated a very interesting selectivity profile against hMAO-A and hMAO-B: some compounds with this scaffold are selective hMAO-A inhibitors, whereas some are selective hMAO-B inhibitors. The small changes in the substituents of the coumarin moiety led to this interesting selectivity profile. The most potent selective hMAO-B inhibitor D7 has a selectivity ratio of 20.93, with an IC₅₀ value of 2.78 μM, similar or better than selegiline (IC₅₀ = 2.89 μM), a selective hMAO-B inhibitor currently in the market for the treatment of Parkinson's disease. Our modeling study indicates that Tyr 326 of hMAO-B (or corresponded Ile 335 of hMAO-A) may be the determinant for the specificity of these compounds. The selectivity profile of compounds reported herein suggests that we can further develop both selective hMAO-A and hMAO-B inhibitors based on this novel scaffold. PMID:26352677

  14. Enantioselective cascade double Michael addition of 3-nitro-2H-chromenes and acyclic enones: efficient synthesis of functionalized tricyclic chroman derivatives.

    PubMed

    Li, Jun-Hua; Du, Da-Ming

    2015-10-01

    An efficient protocol for the asymmetric construction of enantiomerically enriched tetrahydro-6H-benzo[c]chromenes and their derivatives has been developed. The corresponding products were obtained by the cascade double Michael addition of 3-nitro-2H-chromenes and their derivatives with α,β-unsaturated ketones catalyzed by a combination of a quinine-derived primary amine and benzoic acid. Through this methodology, the desired products could be obtained in moderate to good yields (up to 90%), with excellent diastereoselectivities (up to >25 : 1 dr) and moderate to excellent enantioselectivities (up to 95% ee). PMID:26256235

  15. Design and synthesis of novel 2H-chromen-2-one derivatives bearing 1,2,3-triazole moiety as lead antimicrobials.

    PubMed

    Kushwaha, Khushbu; Kaushik, Nagendra; Lata; Jain, Subhash C

    2014-04-01

    A series of novel 2H-chromen-2-one derivatives decorated with 1,2,3-triazole moiety were designed and synthesized using the click reaction of azidoalkyloxy-2H-chromen-2-ones with different propargylamines. Propargylamines were obtained by alkylation of various heterocyclic amines with propargyl bromide. Newly synthesized compounds and intermediates were evaluated for their antifungal activity against four fungi (Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus and Candida albicans). Antibacterial studies were also carried out against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermis) and four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Klebsiella pneumoniae). In vitro, bioassay results showed that all the synthesized compounds exhibited excellent activity against fungal strains Aspergillus fumigatus, Aspergillus flavus and Candida albicans. Interestingly, all the compounds have shown even superior activity than the reference drug miconazole against Aspergillus fumigatus. Morpholine and N-acetyl piperazine containing compounds 10c and 10e have shown promising activity against various bacterial strains. Compound 10e was found to be most active against Pseudomonas aeruginosa. Based on, in silico pharmacokinetic studies, compounds 10a-e were identified as lead compounds for future investigation due to their lower toxicity, high drug score values and good oral bioavailability as per OECD guidelines. PMID:24594353

  16. Crystal structure of 4-methyl-2-oxo-2H-chromen-7-yl ferrocene-carboxyl-ate.

    PubMed

    Yu, Juan; Gao, Lei-Lei; Huang, Peng; Wang, Dian-Lei

    2014-11-01

    The title mol-ecule, [Fe(C5H5)(C16H11O4)], consists of a ferrocenyl moiety and a 4-methyl-coumarin group linked through an ester unit to one of the cyclo-penta-dienyl (Cp) rings. The two Cp rings are virually parallel, with an angle between the two least-squares planes of 0.74 (16)°. The distances between the Fe(II) atom and the centroids of the two Cp rings are 1.639 (2) and 1.652 (2) Å. The conformation of the ferrocenyl moiety is slightly away from eclipsed. The dihedral angle between the coumarin ring system and the ferrocenyl ester moiety is 69.17 (19)°. π-π stacking inter-actions involving the benzene rings of neighbouring coumarin moieties, with centroid-centroid distances of 3.739 (2) Å, consolidate the crystal packing. PMID:25484779

  17. Crystal structure of 8-eth-oxy-3-(4-nitro-phen-yl)-2H-chromen-2-one.

    PubMed

    Walki, Shashikanth; Naveen, S; Kenchanna, S; Mahadevan, K M; Kumara, M N; Lokanath, N K

    2015-11-01

    In the title compound, C17H13NO5, the coumarin ring system is essentially planar (r.m.s. deviation = 0.008 Å). The nitro-phenyl ring makes a dihedral angle of 25.27 (9)° with the coumarin ring plane. The nitro group is almost coplanar with the phenyl ring to which it is attached, making a dihedral angle of 4.3 (3)°. The eth-oxy group is inclined to the coumarin ring plane by 4.1 (2)°. Electron delocalization was found at the short bridging C-C bond with a bond length of 1.354 (2) Å. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming sheets in the bc plane. The sheets are linked via π-π stacking [centroid-centroid distances = 3.5688 (13) and 3.7514 (13) Å], forming a three-dimensional structure. PMID:26594565

  18. 3-[2-(Triphenyl­phosphanyl­idene)acet­yl]-2H-chromen-2-one

    PubMed Central

    Taha, Muhammad; Ismail, Nor Hadiani; Aziza, Ahmad Nazif; Shah, Syed Adnan Ali; Yousuf, Sammer

    2013-01-01

    In the title compound, C29H21O3P, a coumarin-substitued ylid, the P atom is linked to three benzene rings and a planar coumarin moiety via a methyl­enecarbonyl group. The bond lengths in the P=C–C=O fragment clearly indicate a delocalized system involving the olefinic and carbonyl bonds. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O inter­action that results in an S7 graph-set ring motif. In the crystal, mol­ecules are linked into a three-dimensional framework by C—H⋯O hydrogen bonds. PMID:23424524

  19. N'-((2-(6-bromo-2-oxo-2H-chromen-3-yl)-1H-indol-3-yl)methylene)benzohydrazide as a probable Bcl-2/Bcl-xL inhibitor with apoptotic and anti-metastatic potential.

    PubMed

    Kamath, Pooja R; Sunil, Dhanya; Ajees, A Abdul; Pai, K S R; Biswas, Shubankar

    2016-09-14

    A wide number of marketed drugs and drug candidates in cancer clinical development contain halogen substituents. The aim of the present study was to synthesize a series of halogen incorporated indole-coumarin hybrid schiff bases - N'-((2-(2-oxo-2H-chromen-3-yl)-1H-indol-3-yl)methylene)benzohydrazides and to investigate their apoptotic and anti-migratory potential in human breast adenocarcinoma cells as well as to examine their Bcl-2 and Bcl-xL protein binding ability via in silico docking. Hybrid 5g with a bromine atom in position-7 of coumarin ring displayed significant dose dependent cytotoxic activity with high selectivity to MCF-7 cells in MTT assay. Cell cycle progression analysis of 5g treated cells using flow cytometer exhibited a cell cycle arrest in the S phase and accumulation of cells in the subG1 phase. The apoptotic mode of cell death induced by 5g was further confirmed by Annexin-V staining assay. The wound healing assay revealed a profound impairment in the migration of MCF-7 cells presumably due to down-regulation of Bcl-2 and Bcl-xL proteins induced by 5g as observed in immunoblotting analysis. SAR studies of these hybrid molecules based on cell viability and docking were also probed. The most active pharmacophore 5g was found to bind favourably to Bcl-2 and Bcl-xL in docking simulation analysis suggesting it to be a probable small molecule Bcl-2/Bcl-xL inhibitor and a potential lead for breast cancer chemotherapy with apoptotic and anti-metastatic properties. PMID:27187865

  20. Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di­acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis­(pent-4-ynoate)

    PubMed Central

    Akinyemi, Akintunde; Thomas, Courtney; Marsh, Willis; Butcher, Ray J.; Jasinski, Jerry P.; Maynard-Smith, Lystranne A.

    2016-01-01

    In the structures of the two title coumarin derivatives, C14H12O6, (1), and C20H16O6, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by π–π stacking involving the coumarin rings and weak C—H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R 2 2(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π–π stacking. PMID:27308023

  1. Synthesis and evaluation of substituted 4-methyl-2-oxo-2H-chromen-7-yl phenyl carbamates as potent acetylcholinesterase inhibitors and anti- amnestic agents.

    PubMed

    Anand, Preet; Singh, Baldev

    2013-08-01

    The study aimed to synthesize and evaluate substituted 4-methyl-2-oxo-2H-chromen-7-yl phenylcarbamates as potent acetylcholinesterase (AChE) inhibitors and anti-amnestic agents. The compounds were evaluated for AChE and butyrylcholinesterase (BuChE) inhibitory activity in rat brain homogenate and plasma, respectively. The most potent test compound 4d was evaluated for memory testing in scopolamine-induced amnesia. The phenylcarbamate substituted coumarins (4a-4h) demonstrated more potent AChE inhibitory as compared to parent 7-hydroxy-4-methylcoumarin. The introduction of phenylcarbamate moiety to coumarin template also significantly increased BuChE inhibitory activity, albeit less than AChE inhibitory activity with approximate BuChE/AChE selectivity ratio of 20. The compound 4d displayed the most potent AChE inhibitory activity with IC50 = 13.5 ± 1.7 nM, along with amelioration of amnesia in mice in terms of restoration of time spent in target quadrant and escap latency time. It is concluded that carbamate derivatives of coumarin may be employed as potential AChE inhibitors and anti-amnestic agents. PMID:23072555

  2. Synthesis and antibacterial activity of a new series of 3-[3-(substituted phenyl)-1-isonicotinoyl-1H-pyrazol-5-yl]-2H-chromen-2-one derivatives.

    PubMed

    Aragade, Prashant; Maddi, Veeresh; Khode, Suresh; Palkar, Mahesh; Ronad, Pradeepkumar; Mamledesai, Shivalingarao; Satyanarayana, Darbhamulla

    2009-06-01

    A novel series of 3-[3-(substituted phenyl)-1-isonicotinoyl-1H-pyrazol-5-yl]-2H-chromen-2-one derivatives 4a-k have been synthesized by the reaction of 3-[2,3-dibromo-3-(substituted phenyl) propanoyl]-2H-chromen-2-one 3a-k and isonicotinic acid hydrazide in the presence of triethylamine in absolute ethanol, characterized by spectral data and screened for their in-vitro antibacterial activity against Gram-positive and Gram-negative bacteria. Among the series, compounds 4e, 4i, and 4k displayed an encouraging antibacterial activity profile as compared to the reference drug ampicillin against tested bacterial strains. PMID:19475595

  3. Synthesis of novel amide functionalized 2H-chromene derivatives by Ritter amidation of primary alcohol using HBF4·OEt2 as a mild and versatile reagent and evaluation of their antimicrobial and anti-biofilm activities.

    PubMed

    Ratnakar Reddy, K; Poornachandra, Y; Jitender Dev, G; Mallareddy, G; Nanubolu, Jagadeesh B; Kumar, C Ganesh; Narsaiah, B

    2015-08-01

    A series of novel amide functionalized 2H-chromene derivatives 3 were prepared starting from ethyl-2-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylate 1 via sodium borohydride reduction followed by Ritter amidation using HBF4·OEt2 as a mild and versatile reagent. All the products 3 were screened for antimicrobial activity against various Gram-positive, Gram-negative bacteria and fungal strain. The promising derivatives such as 3f, 3g, 3k, 3l, 3m, 3n and 3o were further screened for minimum bactericidal concentration and bio-film inhibition activity and identified the potential ones. Among all the promising, compound 3g was more potent for antimicrobial, MBC and anti bio-film activities. The structure verses activity relationship of 3g revealed that the presence of two bromine atoms at sixth and R position promotes high activity. PMID:26048810

  4. Metal-ligand interaction of lanthanides with coumarin derivatives. Part I. Complexation of 3-(1-aminoethylidene)-2H-chromene-2,4(3H)-dione with La(III), Ce(III), Nd(III) and Ho(III).

    PubMed

    Swiatek, Mirosława; Kufelnicki, Aleksander

    2012-01-01

    Solutions of lanthanum(III), cerium(III), neodymium(III) and holmium(III) nitrates with 3-(1-aminoethylidene)-2H-chromene-2,4(3H)-dione (1) in 10% v/v dioxane-water medium were used. Coordination modes of 1 with the selected lanthanides have been examined. Hydroxo-complexes with deprotonated water molecules from the inner coordination sphere have been stated in basic medium. Stability constants of the forming complex species were determined by potentiometric titrations using Superquad and Hyperquad2003 programs. The most stable complexes are formed with La(III). The UV-Vis spectra of the Nd(III)-1 system confirmed the L:M = 1:1 stoichiometry evaluated potentiometrically. PMID:23285658

  5. Crystal structure of 8-eth­oxy-3-(4-nitro­phen­yl)-2H-chromen-2-one

    PubMed Central

    Walki, Shashikanth; Naveen, S.; Kenchanna, S.; Mahadevan, K. M.; Kumara, M. N.; Lokanath, N. K.

    2015-01-01

    In the title compound, C17H13NO5, the coumarin ring system is essentially planar (r.m.s. deviation = 0.008 Å). The nitro­phenyl ring makes a dihedral angle of 25.27 (9)° with the coumarin ring plane. The nitro group is almost coplanar with the phenyl ring to which it is attached, making a dihedral angle of 4.3 (3)°. The eth­oxy group is inclined to the coumarin ring plane by 4.1 (2)°. Electron delocalization was found at the short bridging C—C bond with a bond length of 1.354 (2) Å. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, forming sheets in the bc plane. The sheets are linked via π–π stacking [centroid–centroid distances = 3.5688 (13) and 3.7514 (13) Å], forming a three-dimensional structure. PMID:26594565

  6. Synthesis and characterization of terbium(III) complexes with the biscoumarin derivative 3,3‧-[(4-hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one)

    NASA Astrophysics Data System (ADS)

    Elenkova, D.; Monov, R.; Tadjer, A.; Manolov, I.; Milanova, M.

    2016-02-01

    Complexes of Tb(III) with the biscoumarin derivative 3,3‧-[(4-hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) are synthesized by using a solution of tetraethylammonium hydroxide, [(C2H5)4N]OH, in water as deprotonating base. Elemental analysis, IR- and fluorescence spectroscopy are used to characterize the samples obtained. The complexes have good fluorescent properties and show the characteristic emission bands of the Tb(III) ion. The triplet state of the mono-deprotonated ligand H2L- was determined. The optimised geometries of the ligand and the complexes were obtained by means of molecular modelling with first principles (DFT) methods.

  7. 6-Methyl-2-oxo-N-(quinolin-6-yl)-2H-chromene-3-carboxamide: crystal structure and Hirshfeld surface analysis

    PubMed Central

    Gomes, Lígia R.; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, Fernanda

    2016-01-01

    The title coumarin derivative, C20H14N2O3, displays intra­molecular N—H⋯O and weak C—H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol­ecule [dihedral angle between the coumarin and quinoline ring systems = 6.08 (6)°]. The supra­molecular structures feature C—H⋯O hydrogen bonds and π–π inter­actions, as confirmed by Hirshfeld surface analyses. PMID:27536395

  8. Crystal structure of 7-[(2E)-2-benzyl­idene-3-oxobut­oxy]-4-methyl-2H-chromen-2-one

    PubMed Central

    Caracelli, Ignez; Zukerman-Schpector, Julio; Moran, Paulo J. S.; de Paula, Bruno R. S.; Tiekink, Edward R. T.

    2015-01-01

    Two independent mol­ecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the mol­ecules relating in particular to the relative orientation of the 3-oxo-2-(phenyl­methyl­idene)but­oxy substituent with respect to the superimposable chromen-2-one residues. To a first approximation, the substituents are mirror images; both are approximately perpendicular to the chromen-2-one fused ring system with dihedral angles of 88.50 (7) (A) and 81.96 (7)° (B). Another difference between the independent mol­ecules is noted in the dihedral angles between the adjacent phenyl and but-3-en-2-one groups of 8.72 (12) (A) and 27.70 (10)° (B). The conformation about the ethene bond in both mol­ecules is E. The crystal packing features C—H⋯O, C—H⋯π(ar­yl) and π–π [Cg⋯Cg = 3.6657 (8) and 3.7778 (8) Å] stacking inter­actions, which generate a three-dimensional network. PMID:26029424

  9. Neptune - full ring system

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57,500 km).

  10. 3-(2-Amino-1,3-thia­zol-4-yl)-6-bromo-2H-chromen-2-one

    PubMed Central

    Chopra, Deepak; Choudhury, A. R.; Venugopala, K. N.; Govender, Thavendran; Kruger, Hendrik G.; Maguire, Glenn E. M.; Guru Row, T. N.

    2009-01-01

    The mol­ecule of the title compound, C12H7BrN2O2S, is essentially planar with a maximum deviation of 0.234 (3) Å from the mean plane through all non-H atoms. The dihedral angle between the coumarin ring plane and that of the five-membered thia­zole ring is 12.9 (1)°. In the crystal, strong N—H⋯O, N—H⋯N and weak but highly directional C—H⋯O hydrogen bonds provide the links between the mol­ecules. In addition, C—H⋯π and π–π inter­actions [centroid–centroid distances = 3.950 (3)–4.024 (3) Å] provide additional stability to the inter­layer regions in the lattice. PMID:21578780

  11. Jovian Ring System Mosaic

    NASA Technical Reports Server (NTRS)

    2000-01-01

    NASA's Galileo spacecraft acquired this mosaic of Jupiter's ring system (top) when the spacecraft was in Jupiter's shadow looking back toward the Sun. Jupiter's ring system (inset diagram) is composed of three parts: an outermost gossamer ring, a flat main ring, and an innermost donut-shaped halo. These rings are made up of dust-sized particles that are blasted off of the nearby inner satellites by small impacts. This image was taken on November 9, 1996 at a distance of 2.3 million kilometers (1.4 million miles).

  12. Effects of the Novel Compound DK223 ([1E,2E-1,2-Bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) on Migration and Proliferation of Human Keratinocytes and Primary Dermal Fibroblasts

    PubMed Central

    Ho, Manh Tin; Kang, Hyun Sik; Huh, Jung Sik; Kim, Young Mee; Lim, Yoongho; Cho, Moonjae

    2014-01-01

    Wound healing plays an important role in protecting the human body from external infection. Cell migration and proliferation of keratinocytes and dermal fibroblasts are essential for proper wound healing. Recently, several studies have demonstrated that secondary compounds produced in plants could affect skin cells migration and proliferation. In this study, we identified a novel compound DK223 ([1E,2E-1,2-bis(6-methoxy-2H-chromen-3-yl)methylene]hydrazine) that concomitantly induced human keratinocyte migration and dermal fibroblast proliferation. We evaluated the regulation of epithelial and mesenchymal protein markers, such as E-cadherin and Vimentin, in human keratinocytes, as well as extracellular matrix (ECM) secretion and metalloproteinase families in dermal fibroblasts. DK223 upregulated keratinocyte migration and significantly increased the epithelial marker E-cadherin in a time-dependent manner. We also found that reactive oxygen species (ROS) increased significantly in keratinocytes after 2 h of DK223 exposure, returning to normal levels after 24 h, which indicated that DK223 had an early shock effect on ROS production. DK223 also stimulated fibroblast proliferation, and induced significant secretion of ECM proteins, such as collagen I, III, and fibronectin. In dermal fibroblasts, DK223 treatment induced TGF-β1, which is involved in a signaling pathway that mediates proliferation. In conclusion, DK223 simultaneously induced both keratinocyte migration via ROS production and fibroblast proliferation via TGF-β1 induction. PMID:25056546

  13. FT-IR and Raman vibrational analysis, B3LYP and M06-2X simulations of 4-bromomethyl-6-tert-butyl-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Sert, Yusuf; Puttaraju, K. B.; Keskinoğlu, Sema; Shivashankar, K.; Ucun, Fatih

    2015-01-01

    In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bacteriostatic and anti-tumor molecule namely, 4-bromomethyl-6-tert-butyl-2H-chromen-2-one have been investigated. The experimental FT-IR (4000-400 cm-1) and Raman spectra (4000-100 cm-1) of the compound in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d, p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

  14. Photo- and thermochromic spirans. 16. * 2-oxo-3-phenyl-5,5-dimethylspiro(1,3-oxazolidine-4,2'-(2H) chromenes)

    SciTech Connect

    Luk'yanov, B.S.; Chernysh, Y.E.; Minkin, V.I.; Nivorozhkin, L.E.

    1986-02-01

    New spirans of the 5,5-dimethyl-3-phenyl-2-oxazolidone series that display photochromic properties in alcohol solutions at about-80/sup 0/C were synthesized. The photoinduced forms are characterized by the presence of two long-wave absorption bands at 350-420 nm and 500-650 nm. The /sup 1/H and /sup 13/C NMR spectra were studied. Anisochronicity of the diastereotopic methyl groups of the oxazolidone ring shows up respectively. only in the /sup 13/C NMR spectra.

  15. Design and in vitro activities of N-alkyl-N-[(8-R-2,2-dimethyl-2H-chromen-6-yl)methyl]heteroarylsulfonamides, novel small molecule Hypoxia Inducible Factor-1 (HIF-1) pathway inhibitors and anti-cancer agents

    PubMed Central

    Mun, Jiyoung; Jabbar, Adnan Abdul; Devi, Narra Sarojini; Yin, Shaoman; Wang, Yingzhe; Tan, Chalet; Culver, Deborah; Snyder, James P.; Van Meir, Erwin G.; Goodman, Mark M.

    2013-01-01

    The Hypoxia Inducible Factor (HIF) pathway is an attractive target for cancer as it controls tumor adaptation to growth under hypoxia and mediates chemo- and radiation resistance. We previously discovered 3,4-dimethoxy-N-[(2,2-dimethyl-2H-chromen-6-yl)methyl]-N-phenylbenzenesulfonamide, as a novel small molecule HIF-1 pathway inhibitor in a high-throughput cell-based assay, but its in vivo delivery is hampered by poor aqueous solubility (0.009 μM in water; logP7.4: 3.7). Here we describe the synthesis of twelve N-alkyl-N-[(8-R-2,2-dimethyl-2H-chromen-6-yl)methyl]heteroarylsulfonamides, which were designed to possess optimal lipophilicities and aqueous solubilities by in silico calculations. Experimental logP7.4 values of 8 of the 12 new analogs ranged from 1.2 ∼ 3.1. Aqueous solubilities of 3 analogs were measured, among which the most soluble N-[(8-methoxy-2,2-dimethyl-2H-chromen-6-yl)methyl]-N-(propan-2-yl)pyridine-2-sulfonamide had an aqueous solubility of 80 μM, e.g. a solubility improvement of ∼9,000-fold. The pharmacological optimization had minimal impact on drug efficacy as the compounds retained IC50 values at or below 5 μM in our HIF-dependent reporter assay. PMID:22746274

  16. Saturn's Spectacular Ring System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  17. Rings in the solar system

    SciTech Connect

    Pollack, J.B.; Cuzzi, J.N.

    1981-11-01

    Saturn, Jupiter, and Uranus have rings with different structure and composition. The rings consist of tiny masses in independent orbits. Photographs and data obtained by the Voyager project have aided in the understanding of Saturn's rings. Spokes have been found in B ring and boards, knots, and twist in F ring. Particles on the order of a micrometer in size are believed to occur in F, B, and A rings. The dominant component is water ice. The rings of Uranus are narrow and separated by broad empty regions. The technique used to study them has been stellar occulation. Nothing is known of particle size. The dominant component is believed to be silicates rich in compounds that absorb sunlight. Jupiter's rings consist of 3 main parts: a bright ring, a diffuse disk, and a halo. Use of Pioneer 10 data and other techniques have indicated particle sizes on the order of several micrometers and some at least a centimeter in diameter. The architecture of the ring system results from the interplay of a number of forces. These include gravitational forces due to moons outside the rings and moonlets embedded in them, electromagnetic forces due to the planet's rotating magnetic field, and even the gentle forces exerted by the dilute gaseous medium in which the rings rotate. Each of these forces is discussed. Several alternative explanations of how the rings arose are considered. The primary difference in these hypotheses is the account of the relationship between the ring particles of today and the primordial ring material. (SC)

  18. 4-Hy-droxy-3-[(4-hy-droxy-2-oxo-2H-3-chromen-yl)(3-thien-yl)meth-yl]-2H-chromen-2-one.

    PubMed

    Asad, Mohammad; Oo, Chuan-Wei; Osman, Hasnah; Rosli, Mohd Mustaqim; Fun, Hoong-Kun

    2011-05-01

    The whole mol-ecule of the title compound, C(23)H(14)O(6)S, is disordered over two sets of sites with refined occupancies of 0.8733 (12):0.1267 (12). The dihedral angle between the mean planes through the chromene ring systems is 56.31 (5) and 55.2 (3)° for the major and minor components, respectively. In both components, a pair of intra-molecular O-H⋯O inter-actions generate rings of S(8) graph-set motif. In the crystal, the mol-ecules are linked by inter-molecular C-H⋯O inter-actions, forming chains along the b axis. The structure is further stabilized by π-π inter-actions with centroid-centroid distances of 3.594 (2) and 3.608 (5) Å. PMID:21754365

  19. Synthesis, in Vitro, and in Vivo Biological Evaluation and Molecular Docking Analysis of Novel 3-(3-oxo-substitutedphenyl-3-)4-(2-(piperidinyl)ethoxy)phenyl)propyl)-2H-chromen-2-one Derivatives as Anti-breast Cancer Agents.

    PubMed

    Dube, Pritam N; Waghmare, Madhuri N; Mokale, Santosh N

    2016-04-01

    The analogs of coumarin-chalcones have been reported to exhibit antineoplastic, anti-allergic, antihepatoprotective, and estrogenic activity. Herein, we have reported 3-(3-oxo-substitutedphenyl-3-)4-(2-(piperidinyl)ethoxy)phenyl)propyl)-2H-chromen-2-one derivatives as a new class of compounds that exhibit selectivity for ER-α binding along with antiproliferative and cytotoxic activity on human breast cancer cell line. The active compounds which show prominent activity against estrogen receptor-alpha-positive (ER+) human breast cancer cell lines MCF-7 and Zr-75-1 are subjected to in vivo screening. The Glide XP docking was performed for designed scaffold to optimize its structural requirement for ER-α inhibition. PMID:26643017

  20. HESYRL storage ring vacuum system

    SciTech Connect

    Li, G.; Pang, Y.; Wang, Y.; Zhou, H.; Zhang, Z.; Jiang, D.; Xu, B.; Xu, S.

    1988-09-30

    The Storage Ring Vacuum System of the Synchrotron Radiation source project of HESYRL (Hefei Synchrotron Radiation Laboratory) in USTC, Hefei, Anhui, China, will be completed this year. Since the designed beam current of the 800 MeV electron storage ring is 300 mA, synchrotron radiation and hence high photon stimulated degassing will occur in the vacuum chamber. In order to get the stored beam lifetime of several hours, the pressure must be maintained at 10/sup -8/ approx.10/sup -9/ Torr. The gas desorption from synchrotron radiation and thermal outgas has been calculated. The UHV system of the storage ring and vacuum pretreatment methods are described in this paper.

  1. Crystal structure of (4E)-4-(8-meth-oxy-2H-chromen-2-yl-idene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one.

    PubMed

    Salim, Muhammad; Munawar, Munawar Ali; Tahir, Muhammad Nawaz; Shahid, Muhammad; Malik, Khizar Iqbal

    2015-06-01

    In the title compound, C20H16N2O3, the phenyl substituent attached to the pyrazole ring makes a dihedral angle of 4.87 (7)° with the rest of the mol-ecule. In the crystal, mol-ecules are connected into inversion dimers of the R 2 (2)(14) type by pairs of C-H⋯O inter-actions. π-π inter-actions exist between the benzene and pyrazole rings at a distance of 3.701 (1) Å. Similarly, π-π inter-actions are present at a centroid-centroid distance of 3.601 (1) Å between the oxygen-containing heterocyclic ring and meth-oxy substituted aromatic ring of a neighbouring mol-ecule. Additional C-H⋯π and C=O⋯π inter-actions are also observed. PMID:26090198

  2. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  3. Crystal structure of (4E)-4-(8-meth­oxy-2H-chromen-2-yl­idene)-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one

    PubMed Central

    Salim, Muhammad; Munawar, Munawar Ali; Tahir, Muhammad Nawaz; Shahid, Muhammad; Malik, Khizar Iqbal

    2015-01-01

    In the title compound, C20H16N2O3, the phenyl substituent attached to the pyrazole ring makes a dihedral angle of 4.87 (7)° with the rest of the mol­ecule. In the crystal, mol­ecules are connected into inversion dimers of the R 2 2(14) type by pairs of C—H⋯O inter­actions. π–π inter­actions exist between the benzene and pyrazole rings at a distance of 3.701 (1) Å. Similarly, π–π inter­actions are present at a centroid–centroid distance of 3.601 (1) Å between the oxygen-containing heterocyclic ring and meth­oxy substituted aromatic ring of a neighbouring mol­ecule. Additional C—H⋯π and C=O⋯π inter­actions are also observed. PMID:26090198

  4. Crystal structure of di-aqua-bis-(7-di-ethyl-amino-3-formyl-2-oxo-2H-chromen-4-olato-κ(2) O (3),O (4))zinc(II) dimethyl sulfoxide disolvate.

    PubMed

    Davis, Aaron B; Fronczek, Frank R; Wallace, Karl J

    2016-07-01

    The structure of the title coordination complex, [Zn(C14H14NO4)2(H2O)2]·2C2H6OS, shows that the Zn(II) cation adopts an octa-hedral geometry and lies on an inversion center. Two organic ligands occupy the equatorial positions of the coordination sphere, forming a chelate ring motif via the O atom on the formyl group and another O atom of the carbonyl group (a pseudo-β-diketone motif). Two water mol-ecules occupy the remaining coordination sites of the Zn(II) cation in the axial positions. The water mol-ecules are each hydrogen bonded to a single dimethyl sulfoxide mol-ecule that has been entrapped in the crystal lattice. PMID:27555957

  5. Crystal structure of di­aqua­bis­(7-di­ethyl­amino-3-formyl-2-oxo-2H-chromen-4-olato-κ2 O 3,O 4)zinc(II) dimethyl sulfoxide disolvate

    PubMed Central

    Davis, Aaron B.; Fronczek, Frank R.; Wallace, Karl J.

    2016-01-01

    The structure of the title coordination complex, [Zn(C14H14NO4)2(H2O)2]·2C2H6OS, shows that the ZnII cation adopts an octa­hedral geometry and lies on an inversion center. Two organic ligands occupy the equatorial positions of the coordination sphere, forming a chelate ring motif via the O atom on the formyl group and another O atom of the carbonyl group (a pseudo-β-diketone motif). Two water mol­ecules occupy the remaining coordination sites of the ZnII cation in the axial positions. The water mol­ecules are each hydrogen bonded to a single dimethyl sulfoxide mol­ecule that has been entrapped in the crystal lattice. PMID:27555957

  6. N-(2-hydroxyethyl)-N,2-dimethyl-8-{[(4R)-5-methyl-3,4-dihydro-2H-chromen-4-yl]amino}imidazo[1,2-a]pyridine-6-carboxamide (PF-03716556), a novel, potent, and selective acid pump antagonist for the treatment of gastroesophageal reflux disease.

    PubMed

    Mori, Hiroki; Tonai-Kachi, Hiroko; Ochi, Yasuo; Taniguchi, Yasuhito; Ohshiro, Hiroyuki; Takahashi, Nobuyuki; Aihara, Takeshi; Hirao, Akiko; Kato, Teruhisa; Sakakibara, Minoru; Kurebayashi, Yoichi

    2009-02-01

    Inhibition of H(+),K(+)-ATPase is accepted as the most effective way of controlling gastric acid secretion. However, current acid suppressant therapy for gastroesophageal reflux disease, using histamine H(2) receptor antagonists and proton pump inhibitors, does not fully meet the needs of all patients because of their mechanism of action. This study sought to characterize the in vitro and in vivo pharmacology of a novel acid pump antagonist, N-(2-Hydroxyethyl)-N,2-dimethyl-8-{[(4R)-5-methyl-3,4-dihydro-2H-chromen-4-yl]amino}imidazo[1,2-a]pyridine-6-carboxamide (PF-03716556), and to compare it with other acid suppressants. Porcine, canine, and human recombinant gastric H(+),K(+)-ATPase activities were measured by ion-leaky and ion-tight assay. The affinities for a range of receptors, ion channels, and enzymes were determined to analyze selectivity profile. Acid secretion in Ghosh-Schild rats and Heidenhain pouch dogs were measured by titrating perfusate and gastric juice samples. PF-03716556 demonstrated 3-fold greater inhibitory activity than 5,6-dimethyl-2-(4-fluorophenylamino)-4-(1-methyl-1,2,3,4-tetrahydroisoquinoline-2-yl)pyrimidine (revaprazan), the only acid pump antagonist that has been available on the market, in ion-tight assay. The compound did not display any species differences, exhibiting highly selective profile including the canine kidney Na(+),K(+)-ATPase. Kinetics experiments revealed that PF-03716556 has a competitive and reversible mode of action. More rapid onset of action than 5-methoxy-2-{[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]-sulfinyl}-benzimidazole (omeprazole) and 3-fold greater potency than revaprazan were observed in Ghosh-Schild rats and Heidenhain pouch dogs. PF-03716556, a novel acid pump antagonist, could improve upon or even replace current pharmacological treatment for gastroesophageal reflux disease. PMID:18981288

  7. Reflex ring laser amplifier system

    DOEpatents

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  8. Wear reduction systems liquid piston ring

    SciTech Connect

    Raymond, R.J.; Chen, T.N.; DiNanno, L.

    1990-09-01

    The overall objective of the program was to demonstrate the technical feasibility of achieving an acceptable wear rate for the cylinder liner, piston, and piston rings in a coal/water-slurry-fueled engine that utilized the concept of a liquid piston ring above the conventional piston rings and to identify technical barriers and required research and development. The study included analytical modeling of the system, a bench study of the fluid motion in the liquid piston ring, and a single-cylinder test rig for wear comparison. A system analysis made on the different variations of the liquid supply system showed the desirability of the once-through version from the standpoint of system simplicity. The dynamics of the liquid ring were modeled to determine the important design parameters that influence the pressure fluctuation in the liquid ring during a complete engine cycle and the integrity of the liquid ring. This analysis indicated the importance of controlling heat transfer to the liquid ring through piston and liner to avoid boiling the liquid. A conceptual piston design for minimizing heat transfer is presented in this report. Results showed that the liquid piston ring effectively reduced the solid particles on the wall by scrubbing, especially in the case where a surfactant was added to the water. The wear rates were reduced by a factor of 2 with the liquid ring. However, leakage of the contaminated liquid ring material past the top ring limited the effectiveness of the liquid ring concept. 8 refs., 33 figs., 1 tab.

  9. Recent observations of Jupiter's ring system

    NASA Astrophysics Data System (ADS)

    Showalter, M.; Burns, J.; de Pater, I.; Hamilton, D.; Horanyi, M.

    2003-04-01

    Jupiter's faint, dusty ring system has several distinct components: a thin main ring, an inner, vertically extended halo, and an outer, fainter pair of "gossamer" rings. This ring system illustrates the complex dynamics of dust after it is ejected from the local moons (Metis, Adrastea, Amalthea and Thebe) and/or embedded parent bodies, and then evolves orbitally under solar and electromagnetic perturbations. The ring system has been observed by four spacecraft (Voyagers 1 and 2, Galileo and Cassini), as well as from the Earth by ground-based observatories and the Hubble Space Telescope (HST). While each individual data set has very limited coverage and content, a complete description of the system is now emerging. This paper will provide a systematic overview of the ring system, based on the latest available data and dynamical models. In particular, the period December 2002 through February 2003 is providing a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while remaining nearly edge-on to the Earth. We will discuss the initial results of an observing program using HST in the visual and the Keck Telescope in the infrared. As the rings pass through opposition, the parent bodies surge in brightness while the dust grains do not; this should provide a new means to distinguish the two populations, better revealing their numbers and locations. Variations in halo thickness with wavelength will provide new information about the sizes and dynamics of the dust grains scattered by Jupiter's strong, inner magnetic field. We will also seek out structures near the outer edge of Amalthea's gossamer ring, hinted at in previous data, which illustrate the dynamics of these dust grains immediately after their initial ejection into the ring.

  10. APS storage ring vacuum system performance

    SciTech Connect

    Noonan, J.R.; Gagliano, J.; Goeppner, G.A.

    1997-06-01

    The Advanced Photon Source (APS) storage ring was designed to operated with 7-GeV, 100-mA positron beam with lifetimes > 20 hours. The lifetime is limited by residual gas scattering and Touschek scattering at this time. Photon-stimulated desorption and microwave power in the rf cavities are the main gas loads. Comparison of actual system gas loads and design calculations will be given. In addition, several special features of the storage ring vacuum system will be presented.

  11. Lectures on algebraic system theory: Linear systems over rings

    NASA Technical Reports Server (NTRS)

    Kamen, E. W.

    1978-01-01

    The presentation centers on four classes of systems that can be treated as linear systems over a ring. These are: (1) discrete-time systems over a ring of scalars such as the integers; (2) continuous-time systems containing time delays; (3) large-scale discrete-time systems; and (4) time-varying discrete-time systems.

  12. Control System of the Small Isochronous ring

    SciTech Connect

    Felix Marti; Eduard Pozdeyev

    2004-07-01

    The purpose of this paper is to describe the control system of the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Information about the electronics used and software written to control different injection line, ring and extraction line elements is included. Some of these elements are magnets, electrostatic quadrupoles, electric and magnetic correctors, scanning wires, emittance measurement system, chopper and a fast Faraday cup.

  13. RF SYSTEM FOR THE SNS ACCUMULATOR RING.

    SciTech Connect

    BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

    2001-06-18

    During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed.

  14. The Conversion of Wiswesser Line Notations to Ring Codes. I. The Conversion of Ring Systems

    ERIC Educational Resources Information Center

    Granito, Charles E.; And Others

    1972-01-01

    The computerized conversion of Wiswesser Line Notations to Ring Codes, using a two-part approach, and the set of computer programs generated for the conversion of ring systems are described. (9 references) (Author)

  15. APS storage ring vacuum system development

    SciTech Connect

    Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Ferry, R.; Goeppner, G.A.; Gonczy, J.D.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

    1991-01-01

    The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's materials research program. The Storage Ring's 1104 m circumference is divided into 40 sectors which contain vacuum, beam transport, control, rf and insertion device systems. The vacuum system will operate at a pressure of 1 nTorr and is fabricated from aluminum. The system includes distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. An overview of the vacuum system design and details of selected development program results are presented. 5 refs.

  16. The ALS Storage Ring RF System

    SciTech Connect

    Taylor, B.; Lo, C.C.; Baptiste, K.; Guigli, J.; Julian, J.

    1993-05-01

    The ALS Storage Ring RF System is characterized by the use of the following features: (1) High power loading of two single cell cavities. (2) The use of a tubular ceramic input window employing aperture coupling. (3) The use of waveguide filters and matchers designed for HOM absorption. (4) A comprehensive HOM monitoring system. (5) The use of waveguide water-wedge loads for the magic tee and circulator loads. The results of cavity measurements and high power tests are reported together with the performance of the system during the commissioning and operation phases of the ALS project. Plans for future window development are discussed.

  17. Electrodynamic processes in the ring system of Saturn

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.; Hill, J. R.; Ip, W.-H.; Goertz, C. K.; Gruen, E.

    1984-01-01

    A number of recently observed Saturn ring phenomena are discussed in terms of their electrodynamic implications. Voyager 1 and 2 observations of the rotating near-radial spokes in the B Ring, waves and braids of the F Ring, and discrete episodic bursts of broadband radio emission, claimed by some to originate in a ring, are addressed. Several other phenomena are considered, including the origin and evolution of the diffuse E Ring and G Ring (which appear to be composed of fine dust), as well as the existence of a number of sharp discontinuities in the main ring system, within the context of gravitoelectrodynamics of charged dust in the magnetosphere.

  18. Reliable Fiber Sensor System with Star-Ring-Bus Architecture

    PubMed Central

    Peng, Peng-Chun; Wang, Jun-Bo; Huang, Kuan-Yan

    2010-01-01

    This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems. PMID:22399876

  19. Crystal structures of two hydrazinecarbo­thio­amide derivatives: (E)-N-ethyl-2-[(4-oxo-4H-chromen-3-yl)methyl­idene]hydrazinecarbo­thio­amide hemi­hydrate and (E)-2-[(4-chloro-2H-chromen-3-yl)methyl­idene]-N-phenyl­hydrazinecarbo­thio­amide

    PubMed Central

    Gangadharan, Rajeswari; Haribabu, Jebiti; Karvembu, Ramasamy; Sethusankar, K.

    2015-01-01

    The title compounds, C13H13N3O2S·0.5H2O, (I), and C17H14ClN3OS, (II), are hydrazinecarbo­thio­amide derivatives. Compound (I) crystallizes with two independent mol­ecules (A and B) and a water mol­ecule of crystallization in the asymmetric unit. The chromene moiety is essentially planar in mol­ecules A and B, with maximum deviations of 0.028 (3) and 0.016 (3) Å, respectively, for the carbonyl C atoms. In (II), the pyran ring of the chromene moiety adopts a screw-boat conformation and the phenyl ring is inclined by 61.18 (9)° to its mean plane. In the crystal of (I), bifurcated N—H⋯O and C—H⋯O hydrogen bonds link the two independent mol­ecules forming A–B dimers with two R 2 1(6) ring motifs, and R 2 2(10) and R 2 2(14) ring motifs. In addition to these, the water mol­ecule forms tetra­furcated hydrogen bonds which alternately generate R 4 4(12) and R 6 6(22) graph-set ring motifs. There are also π–π [inter-centroid distances = 3.5648 (14) and 3.6825 (15) Å] inter­actions present, leading to the formation of columns along the c-axis direction. In the crystal of (II), mol­ecules are linked by pairs of N—H⋯S hydrogen bonds, forming inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C—H⋯π inter­actions, forming ribbons lying parallel to (210). PMID:25844194

  20. Cooling system for three hook ring segment

    SciTech Connect

    Campbell, Christian X.; Eng, Darryl; Lee, Ching-Pang; Patat, Harry

    2014-08-26

    A triple hook ring segment including forward, midsection and aft mounting hooks for engagement with respective hangers formed on a ring segment carrier for supporting a ring segment panel, and defining a forward high pressure chamber and an aft low pressure chamber on opposing sides of the midsection mounting hook. An isolation plate is provided on the aft side of the midsection mounting hook to form an isolation chamber between the aft low pressure chamber and the ring segment panel. High pressure air is supplied to the forward chamber and flows to the isolation chamber through crossover passages in the midsection hook. The isolation chamber provides convection cooling air to an aft portion of the ring segment panel and enables a reduction of air pressure in the aft low pressure chamber to reduce leakage flow of cooling air from the ring segment.

  1. Keck Observations of Dusty Rings in our Solar System

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2007-08-01

    All four giant planets are surrounded by ring systems, which typically consist of a combination of large and small bodies, as well as fine dust. With the 10-m W.M. Keck telescope on Mauna Kea (Hawaii) we have focused on observing the dusty rings of these planets. In this review I will summarize our data sets. I will focus on our most recent results with regard to Jupiter and Uranus, both observed during ring plane crossings. Jupiter's ring system was observed in December 2002 and January 2003 at 2.2 micron, where we used both the facility near-infrared camera NIRC with a pixel size of 0.151" (˜500 km at Jupiter), and the adaptive optics camera NIRC2, with a pixelsize of 0.04" and 0.01". The images were "onion-peeled" to provide radial scans of the rings. We will compare results of the main ring with Galileo data, and comment on similarities and differences with respect to the location of parent material in the ring. The radial structure of the gossamer rings is very different than expected based upon the Burns et al (1999) formation scenarios. The rings are not sheets of material, but narrow rings located just interior to the orbits of Amalthea and Thebe. The Amalthea ring shows a structure analagous to the main ring. Its inner boundary is near the location of synchronous orbit. Radial variations in the Thebe ring suggest "sculpting" by Lorentz resonances. We will present images of Uranus "hot of the press"; we are scheduled to observe in July and August when the rings are edge-on.

  2. Wind turbine ring/shroud drive system

    DOEpatents

    Blakemore, Ralph W.

    2005-10-04

    A wind turbine capable of driving multiple electric generators having a ring or shroud structure for reducing blade root bending moments, hub loads, blade fastener loads and pitch bearing loads. The shroud may further incorporate a ring gear for driving an electric generator. In one embodiment, the electric generator may be cantilevered from the nacelle such that the gear on the generator drive shaft is contacted by the ring gear of the shroud. The shroud also provides protection for the gearing and aids in preventing gear lubricant contamination.

  3. Weak dynamical effects in the Uranian ring system

    NASA Technical Reports Server (NTRS)

    Freedman, A. P.; Tremaine, S.; Elliot, J. L.

    1983-01-01

    Published data on the orbits of the rings and satellites of Uranus are analyzed in terms of their dynamic interaction, in an attempt to explain discrepancies between current kinematic models of the ring system and recent, very accurate occultation observations. Apse precession, short-term perturbations, satellite resonance, and the movement of the planet and rings with respect to the barycenter of the planet-satellite system are investigated. It is found that the five known satellites could cause the observed ring residuals by shifting the barycenter, but not by direct or resonance effects. Hypothetical interring shepherd satellites of limited mass (such as about 10 to the 19th g for a shepherd between rings 4 and 5), possibly affected by known-satellite resonances, could influence the rings directly.

  4. Recent Hubble Observations of Jupiter's Ring System

    NASA Astrophysics Data System (ADS)

    Showalter, M. R.; Burns, J. A.; de Pater, I.; Hamilton, D. P.; Horanyi, M.

    2003-05-01

    The period December 2002 through February 2003 provided a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while the rings remained nearly edge-on to Earth. We used this period for a series of Jovian ring observations using the High Resolution Channel (HRC) of Hubble's new Advanced Camera for Surveys (ACS). Phase angles span 0.17o--10o. Our images showed the main ring, Adrastea and Metis with very high signal-to-noise ratios (SNR). Amalthea's gossamer ring was detected (and vertically resolved) in a small set of specially targeted images. Somewhat surprisingly, we have not yet been able to detect the halo in any of our images, perhaps because it is obscured by the scattered light from Jupiter's disk, positioned just 4'' outside the HRC's field of view. Preliminary results from this data set are as follows. (1) The ring is substantially less red than the moons, suggesting that fine dust represents a significant fraction of its backscattering intensity. (2) Neither the rings nor the embedded moons Metis and Adrastea have significant opposition surges. We were hoping to use the surge, which is characteristic of most macroscopic bodies but not dust, as an indicator of where any embedded ring parent bodies might reside. (3) Because our data are so sensitive to Metis (radius ˜ 20 km) and Adrastea ( ˜ 8 km), we believe that bodies as small as 3--4 km in radius should have been detected in the data. In an initial search, no additional bodies have been detected. (4) The Amalthea ring shows an enhancement in brightness in its outermost 15,000 km. This is consistent with what was seen in Galileo images at very high phase angles. Support for this work was provided by NASA through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS5-26555.

  5. Ring-laser gyroscope system using dispersive element(s)

    NASA Technical Reports Server (NTRS)

    Smith, David D. (Inventor)

    2010-01-01

    A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

  6. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  7. Superfluid qubit systems with ring shaped optical lattices

    PubMed Central

    Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan

    2014-01-01

    We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit. PMID:24599096

  8. Rings

    SciTech Connect

    Davis, R.L.

    1989-01-01

    The essence of vortex physics is that at certain low-energy scales elementary excitations of a point particle theory can behave like strings rather than particles. Vortices are the resulting string-like solutions; their thickness sets the distance scale beyond which physics is string-like rather than particle-like. String degrees of freedom are massless in the sense that excitations on a string can have an arbitrarily low frequency. Non-string degrees of freedom correspond to massive particles and are absent from the low energy spectrum. This article considers only field theories with vortices at low energies. The possible existence of a class of solitons in these vortex theories will be discussed. They are vortex rings: they are localized and finite in energy, and able to carry the quantum numbers of point particles. Rings are thus particle-like solutions of a vortex theory, which is itself a limit of a point particle field theory.

  9. News Note: Possible Ring System found around a Minor Planet

    NASA Astrophysics Data System (ADS)

    Editors

    2015-04-01

    Astronomers at the SAAO and the Massachusetts Institute of Technology (MIT), USA have recently detected what may be rings around Chiron, a minor planet in our solar system. Full paper published in Icarus (Ruprecht, J. et al).

  10. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  11. A ring system detected around the Centaur (10199) Chariklo.

    PubMed

    Braga-Ribas, F; Sicardy, B; Ortiz, J L; Snodgrass, C; Roques, F; Vieira-Martins, R; Camargo, J I B; Assafin, M; Duffard, R; Jehin, E; Pollock, J; Leiva, R; Emilio, M; Machado, D I; Colazo, C; Lellouch, E; Skottfelt, J; Gillon, M; Ligier, N; Maquet, L; Benedetti-Rossi, G; Ramos Gomes, A; Kervella, P; Monteiro, H; Sfair, R; El Moutamid, M; Tancredi, G; Spagnotto, J; Maury, A; Morales, N; Gil-Hutton, R; Roland, S; Ceretta, A; Gu, S-h; Wang, X-b; Harpsøe, K; Rabus, M; Manfroid, J; Opitom, C; Vanzi, L; Mehret, L; Lorenzini, L; Schneiter, E M; Melia, R; Lecacheux, J; Colas, F; Vachier, F; Widemann, T; Almenares, L; Sandness, R G; Char, F; Perez, V; Lemos, P; Martinez, N; Jørgensen, U G; Dominik, M; Roig, F; Reichart, D E; LaCluyze, A P; Haislip, J B; Ivarsen, K M; Moore, J P; Frank, N R; Lambas, D G

    2014-04-01

    Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ±  9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites. PMID:24670644

  12. Feedback invariants for linear systems defined over rings

    NASA Technical Reports Server (NTRS)

    Byrnes, C. I.

    1979-01-01

    A coefficient-assignability theorem is presented for systems defined over a commutative ring with 1. The conditions examined include all the general results on coefficient-assignability available in the literature. It is concluded that the proposed techniques are not effective for the case of the weaker property of pole placement when it is assumed that the commutative ring is a PID. Morse's well-known theorem seems to be the best result available for this situation.

  13. 4-Bromo­methyl-6-tert-butyl-2H-chromen-2-one

    PubMed Central

    Nagarajaiah, H.; Puttaraju, K. B.; Shivashankar, K.; Begum, Noor Shahina

    2013-01-01

    In the crystal structure of the title compound, C14H15BrO2, weak C—H⋯O inter­actions link the mol­ecules into zigzag chains extending along the c-axis direction. These chains are further assembled into (100) layers via π–π stacking inter­actions between inversion-related chromenone fragments [inter­planar distance = 3.376 (2) Å]. PMID:24046630

  14. Numerical modeling of Saturn's satellites and ring system

    NASA Astrophysics Data System (ADS)

    Chambers, Lindsey Starr

    2008-10-01

    Saturn's extensive ring and satellite system make it one of the most fascinating bodies in the solar system. Space missions like Cassini have revolutionized our understanding of the Saturn system; however, many issues remain unresolved. This dissertation explores three projects related to unanswered questions about Saturn's rings and satellites. Published moment of inertia data provide weak constraints on the interior structure of Saturn's mid-sized icy satellites. Giant impact basins and their associated antipodal terrains provide an alternate way to study the satellites' interior structures. I used hydrodynamical impact simulations to assess the amount of damage caused to the antipodal terrain of Tethys, Mimas and Rhea. Results vary somewhat from one satellite to another due to differences in the sizes of the satellites and impactors. I find that antipodal disruption depends more on core radius than core density, suggesting that core geometry may express a surface signature in global impacts on partially differentiated targets. The flux of meteoroids impacting Saturn's rings is not well known; this has important implications for the age of the rings. One way to better constrain this flux is to observe flashes caused by hypervelocity impacts between meteoroids and ring particles. 400 hours of ultraviolet Cassini observations were initially allotted to search for impact flashes. I used a hydrodynamics code to simulate such impacts and developed a radiative transfer model to study the resulting impact plumes. I find that the impact plumes last for only 10- 4 s, and radiation from the impact plumes is emitted in the visible rather than ultraviolet. The albedos of the ring particles are not well constrained. This directly relates to the composition of the rings and has implications for their age. I developed a radiative transfer code to model photon interactions with ring particles. This code includes the volume filling factor and demonstrates that inclusion of

  15. Gravito-electrodynamics and the structure of planetary ring systems

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.

    1984-01-01

    Recent spacecraft observations of the Saturnian and Jovian ring systems have highlighted a plethora of interesting new phenomena associated with those regions containing fine (micron and sub-micron sized) dust. Recognizing that these dust grains, by virtue of being immersed within the planetary magnetospheres, are electrostatically charged to the point that they experience comparable gravitational and electric forces, a new 'gravito-electrodynamic' theory has been developed to describe their dynamics. This theory has been successful in explaining all these phenomena in a systematic way. In this review, the basic model and its range of validity are outlined, and its application to the Saturnian and Jovian ring systems are discussed.

  16. Gravito-electrodynamics and the structure of planetary ring systems

    NASA Astrophysics Data System (ADS)

    Mendis, D. A.

    1984-08-01

    Recent spacecraft observations of the Saturnian and Jovian ring systems have highlighted a plethora of interesting new phenomena associated with those regions containing fine (micron and sub-micron sized) dust. Recognizing that these dust grains, by virtue of being immersed within the planetary magnetospheres, are electrostatically charged to the point that they experience comparable gravitational and electric forces, a new 'gravito-electrodynamic' theory has been developed to describe their dynamics. This theory has been successful in explaining all these phenomena in a systematic way. In this review, the basic model and its range of validity are outlined, and its application to the Saturnian and Jovian ring systems are discussed.

  17. SIMULATION STUDY AND INITIAL TEST OF THESNS RING RF SYSTEM

    SciTech Connect

    Zhang, Yan; Ma, Hengjie; Holmes, Jeffrey A; Champion, Mark; Chu, Paul; Cousineau, Sarah M; Hardek, Thomas W; Plum, Michael A; Danilov, Viatcheslav; Piller, Chip

    2008-01-01

    The rfsimulator code was developed for the study of the Spallation Neutron Source (SNS) dual-harmonic ring RF control. It uses time-domain solvers to compute beam-cavity interactions and FFT methods to simulate the time responses of the linear RF system. The important elements of the system considered in the model include beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral controller for feedback and adaptive feed forward, stochastic noise, width-in-turn loop parameter change, beam current fluctuation, and bunch leakage. As the beam power increases, beam loss in the ring goes up and thus precise control of the bunching RF phase and amplitude is required to limit beam loss. The code will help in the development of a functional RF control and in achieving the goal of minimizing beam loss in the accumulator ring.

  18. Clump detections and limits on moons in Jupiter's ring system.

    PubMed

    Showalter, Mark R; Cheng, Andrew F; Weaver, Harold A; Stern, S Alan; Spencer, John R; Throop, Henry B; Birath, Emma M; Rose, Debi; Moore, Jeffrey M

    2007-10-12

    The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role. PMID:17932287

  19. Rf System Requirements for JLab’s MEIC Collider Ring

    SciTech Connect

    Wang, Shaoheng; Li, Rui; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2013-06-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. At the top energy are the electron and ion collider rings. For the ion ring, it accelerates five long ion bunches to colliding energy and rebunches ions into a train of very short bunches before colliding. A set of low frequency RF system is needed for the long ion bunch energy ramping. Another set of high frequency RF cavities is needed to rebunch ions. For the electron ring, superconducting RF (SRF) cavities are needed to compensate the synchrotron radiation energy loss. The impedance of the SRF cavities must be low enough to keep the high current electron beam stable. The preliminary design requirements of these RF cavities are presented.

  20. Position Ring System using Anger Type Detectors

    SciTech Connect

    Joel S. Karp, principal investigator

    2004-12-14

    The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.

  1. Local stability criterion for the Saturnian ring system

    NASA Astrophysics Data System (ADS)

    Griv, Evgeny

    1998-02-01

    The self-gravitating particulate disk of the Saturnian ring system is studied using linear theory to determine its evolution and stability against gravitational Jeans-type perturbations. The analysis is carried out in approximation of the basically homogeneous and two-dimensional system. In addition, the case is considered with rare collisions between particles when the squared epicyclic frequency κ2 as well as the squared orbital angular frequency Ω 2 greatly exceeds the squared frequency of interparticle physical collisions νc2; that is, the analysis presented here is valid only in the regime of low optical depth in Saturn's rings, τ⋍ ν c/Ω<1 . According to observations, such low optical depth regions can be found in the C ring, the inner portions of the B ring at distances r<100 000 km and the A ring at distances r>123 000 km from the planetary center. The analogy with magnetized plasma problems is utilized by applying the so-called single particle dynamics method (the Lagrangian description): The motion of an "average" particle is considered. In the framework of this analytical method the local dispersion relation for small-amplitude oscillations is derived. Using the dispersion relation, an analysis is given of the dispersion law both for axisymmetric (radial) and nonaxisymmetric (spiral) Jeans perturbations. The main result, which follows from the dispersion relation, is the local stability criterion. The criterion generalizes the well-known Toomre's one ( Astrophys. J.139, 1217-1238, 1964) for spiral gravity perturbations. The dynamical behavior of the different models of Saturn's ring disk is studied by N-body computer simulations in order to confirm the validity of the generalized stability criterion. The numerical method of local simulations (or N-body simulations in a Hill's approximation) is applied. It is shown that the stability criterion obtained from the computer models is in general agreement with the theoretical prediction. It is proposed

  2. A Transiting Extrasolar Ring System: Indirect Evidence for Exosatellite Formation?

    NASA Astrophysics Data System (ADS)

    Mamajek, Eric E.

    2015-08-01

    The young star 1SWASP J140747.93-394542.6 ("J1407") is a 16-million-year-old pre-main sequence star in Sco-Cen, the nearest OB association. In 2012, we reported that time series photometry data from the SuperWASP and ASAS programs show that the star J1407 had a series of extremely complex eclipses over a two-month span in early 2007, with ~95% of the star's light blocked out near minimum. The star J1407 shows no evidence for accretion nor any circumstellar disk blueward of the WISE4 IR band. The eclipses have been modeled as due to a set of (at least 30) concentric dust rings with total mass of approximately 1 Earth mass, with radii ranging from approximately 30-90 million km. There is at least one very clean gap in the ring system at radius ~0.4 AU which may be cleared by a sub-Earth-size exosatellite. While popularly described as a "super-Saturn" with "rings", given the age of the system, and the size and inferred mass of the rings, it seems plausible that we are detecting a circumplanetary (or protoexosatellite) disk. The disk would appear to fill a non-negligible fraction of its Hill radius, and the appearance of gaps would suggest that system is in the process of spawning exosatellites. I will summarize the current knowledge about the J1407 system: including archival and on-going photometric searches for additional eclipses, imaging and Doppler constraints on the companion of the ringed companion, and future prospects for discovering eclipsing disks girding young exoplanets and substellar objects.

  3. Documentation for the token ring network simulation system

    NASA Technical Reports Server (NTRS)

    Peden, Jeffery H.; Weaver, Alfred C.

    1990-01-01

    A manual is presented which describes the language features of the Token Ring Network Simulation System. The simulation system is a powerful simulation tool for token ring networks which allows the specification of various Medium Access Control (MAC) layer protocols as well as the specification of various features of upper layer ISO protocols. In addition to these features, it also allows the user to specify message and station classes virtually to any degree of detail desired. The choice of a language instead of an interactive system to specify network parameters was dictated by both flexibility and time considerations. The language was developed specifically for the simulation system, and is very simple. It is also user friendly in that language elements which do not apply to the case at hand are ignored rather than treated as errors.

  4. BPM SYSTEM FOR THE SNS RING AND TRANSFER LINES.

    SciTech Connect

    DAWSON,W.C.; CAMERON,P.; CERNIGLIA,P.; CUPOLO,J.; DEGEN,C.; DELLAPENNA,A.; HUHN,A.; KESSELMAN,M.; MEAD,J.; SIKORA,R.

    2002-05-06

    The Spallation Neutron Source Ring accumulates about 1060 pulses of 38mA peak current IGeV H-minus particles from the Linac thru the HEBT line, then delivers this accumulated beam in a single pulse to the mercury target via the RTBT line. Bunching frequency of beam in the HEBT line is 402.5MHz, and about 1MHz in the Ring and RTBT. Position monitor electrodes in HEBT are of the shorted stripline type, with apertures of 12cm except in the dispersive bend, where the aperture is 21cm. Ring and RTBT electrodes are open striplines, with apertures of 21, 26, 30, and 36cm. All pickups are dual plane. The electronics will be PC-based with the Analog/Digital Front End passing data and receiving control and timing thru a custom PC1 interface developed by LANL[l]. LabVIEW will be used to direct the acquisition, process the data, and transfer results via Ethernet to the EPICS control system. To handle the dynamic range required with well over 60dB variation in signal size, the Ring and RTBT electronics will employ a fast gain switching technique that will take advantage of the 300ns tail-to-head gap to provide position measurement during the entire accumulation cycle. Beam-based alignment will be utilized as part of the system calibration.

  5. BPM System for the SNS Ring and Transfer Lines

    NASA Astrophysics Data System (ADS)

    Dawson, W. C.; Cameron, P.; Cerniglia, P.; Cupolo, J.; Degen, C.; DellaPenna, A.; Huhn, A.; Kesselman, M.; Mead, J.; Sikora, R.

    2002-12-01

    The Spallation Neutron Source Ring accumulates about 1060 pulses of 38mA peak current 1GeV H-minus particles from the Linac thru the HEBT line, then delivers this accumulated beam in a single pulse to the mercury target via the RTBT line. Bunching frequency of beam in the HEBT line is 402.5MHz, and about 1MHz in the Ring and RTBT. Position monitor electrodes in HEBT are of the shorted stripline type, with apertures of 12cm except in the dispersive bend, where the aperture is 21cm. Ring and RTBT electrodes are open striplines, with apertures of 21, 26, 30, and 36cm. All pickups are dual plane. The electronics will be PC-based with the Analog/Digital Front End passing data and receiving control and timing thru a custom PCI interface developed by LANL[1]. LabVIEW will be used to direct the acquisition, process the data, and transfer results via Ethernet to the EPICS control system. To handle the dynamic range required with well over 60dB variation in signal size, the Ring and RTBT electronics will employ a fast gain switching technique that will take advantage of the 300ns tail-to-head gap to provide position measurement during the entire accumulation cycle. Beam-based alignment will be utilized as part of the system calibration.

  6. A conceptual Saturn ring observer mission using standard radioisotope power systems

    NASA Technical Reports Server (NTRS)

    Abelson, Robert D.; Spilker, Thomas R.

    2006-01-01

    Saturn remains of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields.

  7. Dust in the Jovian System: Streams, Clouds and Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Gruen, E.

    2003-04-01

    Spacecraft investigations during the last ten years have vastly improved our knowledge about dust in the Jovian system. All Galilean satellites, and probably all smaller satellites as well, are sources of dust in the Jovian system. In-situ measurements with the dust detectors on board the Ulysses and Galileo spacecraft have for the first time demonstrated the electromagnetic interaction of charged dust grains with the interplanetary magnetic field and with a planetary magnetosphere. Jupiter's magnetosphere acts as a giant mass-velocity spectrometer for charged 10-nanometer dust grains. These grains are released from Jupiter's moon Io with a typical rate of ˜ 1 kg s-1. The seven-year long record of Galileo in-situ dust measurements revealed significant variations of the fluxes of the dust stream particles with Jovian local time which are caused by the dawn-dusk asymmetry of the Io plasma torus. The streams probe the plasma conditions in the torus, and they can be used as a potential monitor of Io's volcanic plume activity. The joint Galileo-Cassini dust measurements at Jupiter imply stream particle speeds up to 400 km s-1. All Galilean satellites are surrounded by tenuous impact-generated clouds of mostly sub-micrometer ejecta grains. Jovian rings not only exist in the well-known region of the main and gossamer rings but also much farther out. Very tenuous rings composed of mostly micron-sized grains have been detected in-situ in the region between the Galilean moons and further beyond out to ˜ 250 R_J from the planet. The dust densities there are much too low to allow detection with imaging techniques. The measurements have demonstrated that impact-ejecta derived from hypervelocity impacts onto satellites are the major constituent of dusty planetary rings. On 5 November 2002 Galileo traversed Jupiter's gossamer rings for the first time and had a close flyby at Amalthea. Several hundred dust impacts have been detected during this passage with the dust detector on

  8. READOUT SYSTEM FOR ARRAYS OF FRISCH-RING CDZNTE DETECTORS.

    SciTech Connect

    CUI, Y.; BOLOTNIKOV, A.E.; CAMARDA, G.S.; DE GERONIMO, G.; O'CONNOR, P.; JAMES, R.B.; KARGAR, A.; HARRISON, M.J.; MCGREGOR, D.S.

    2006-10-29

    Frisch-ring CdZnTe detectors have demonstrated good energy resolution for identifying isotopes, <1% FWHM at 662 keV, and good efficiency for detecting gamma rays. We will fabricate and test at Brookhaven National Laboratory an integrated module of a 64-element array of 6 x 6 x 12 mm{sup 3} Frisch-ring detectors, coupled with a readout electronics system. It supports 64 readout channels, and includes front-end electronics, signal processing circuit, USB interface and high-voltage power supply. The data-acquisition software is used to process the data stream, which includes amplitude and timing information for each detected event. This paper describes the design and assembly of the detector modules, readout electronics, and a conceptual prototype system. Some test results are also reported.

  9. Quantum interference in an electron-hole graphene ring system

    SciTech Connect

    Smirnov, D.; Schmidt, H.; Haug, R. J.

    2013-12-04

    Quantum interference is observed in a graphene ring system via the Aharonov Bohm effect. As graphene is a gapless semiconductor, this geometry allows to study the unique situation of quantum interference between electrons and holes in addition to the unipolar quantum interference. The period and amplitude of the observed Aharonov-Bohm oscillations are independent of the sign of the applied gate voltage showing the equivalence between unipolar and dipolar interference.

  10. Uranus. [Scientific study of planetary structure, ring systems, and magnetosphere

    SciTech Connect

    Bergstralh, J.T.

    1987-03-01

    Observations and theoretical investigations of the Uranus (U) system from the period 1983-1986 are reviewed, with an emphasis on the Voyager 2 encounter with U on January 26, 1986. Topics addressed include the bulk U composition, structure, and heat flux; the U atmospheric composition, structure, and circulation; the U rings; the major and minor U satellites; the U magnetosphere; and the Lyman-alpha 'electroglow' observed on the sunlit hemisphere of U. 191 references.

  11. Evolution of ring-field systems in microlithography

    NASA Astrophysics Data System (ADS)

    Williamson, David M.

    1998-09-01

    Offner's ring-field all-reflecting triplet was the first successful projection system used in microlithography. It evolved over several generations, increasing NA and field size, reducing the feature sizes printed from three down to one micron. Because of its relative simplicity, large field size and broad spectral bandwidth it became the dominant optical design used in microlithography until the early 1980's, when the demise of optical lithography was predicted. Rumours of the death of optics turned out to be exaggerated; what happened instead was a metamorphosis to more complex optical designs. A reduction ring-field system was developed, but the inevitable loss of concentricity led to a dramatic increase in complexity. Higher NA reduction projection optics have therefore been full-field, either all-refracting or catadioptric using a beamsplitter and a single mirror. At the present time, the terminal illness of optical lithography is once again being prognosed, but now at 0.1 micro feature sizes early in the next millenium. If optics has a future beyond that, it lies at wavelengths below the practical transmission cut-off of all refracting materials. Scanning all-reflecting ring-field systems are therefore poised for a resurgence, based on their well-established advantage of rotational symmetry and consequent small aberration variations over a small, annular field. This paper explores some such designs that potentially could take optical lithography down to the region of 0.025 micron features.

  12. BETA PICTORIS DISK HIDES GIANT ELLIPTICAL RING SYSTEM

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A NASA Hubble Space Telescope false-color, visible-light picture of one side of the edge-on dust disk around the star Beta Pictoris. Knots in the disk (marked A,B,C,D) are interpreted as rings of dust, seen edge-on. Image credit: NASA and Paul Kalas (Space Telescope Science Institute) A still frame from a computer simulation, which shows a circumstellar dust disk highly perturbed by the gravitational pull of a bypassing star. The gray solid area represents the initial shape and size of the undisturbed disk. In the simulation, the gravity of the passing star rearranges the orbit of each particle, setting up an elliptical ring system that may have survived for the last 100,000 years since the impact occurred.

  13. The fluid systems for the SLD Cherenkov ring imaging detector

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw, H.; Simopoulos, C.; Solodov, E.; Toge, N.; Vavra, J.; Watt, R.; Weber, T.; Williams, S.H.; Baird, K.; Jacques, P.; Kalelkar, M.; Plano, R.; Stamer, P.; Word, G.; Bean, A.; Caldwell, D.O.; Duboscq, J.; Huber, J.; Lu, A.; Mathys, L.; McHugh, S.; Yellin, S.; Ben-David, R.; Manly, S.; Snyder, J.; Turk, J.; Cavalli-Sforza, M.; Coyle, P.; Coyne, D.; Gagnon, P.; Liu, X.; Schneider, M.; Williams, D.A.; Coller, J.; Shank, J.T.; Whitaker, J.S.; d`Oliveira, A.; Johnson, R.A.; Martinez, J.; Nussbaum, M.; Santha, A.K.S.; Sokoloff, M.D.; Stockdale, I.; Wilson, R.J.

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C{sub 2}H{sub 6} + TMAE), radiator gas (C{sub 5}F{sub 12} + N{sub 2}) and radiator liquid (C{sub 6}F{sub 14}). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  14. RF system at HIRFL-CSR main ring

    NASA Astrophysics Data System (ADS)

    Zhang, W. Z.; Zhang, D. S.; Zhan, W. L.

    2001-12-01

    A heavy ion cooler-storage ring HIRFL-CSR[1] has been constructed at IMP. It consists of a main ring (CSRm) and an experimental ring (CSRe). Two RF cavities will be employed for CSRm. One is for beam acceleration, and another is for beam RF stacking. The accelerating cavity is designed to accelerate the beam from 10-50 MeV/u to 400-900 MeV/u with harmonic number h=1. The peak RF voltage is 8.0 kV and frequency range is from 0.25 MHz to 1.7 MHz. The RF stacking cavity with maximum voltage amplitude of 20 kV and tunable frequency range 6.0-14.0 MHz is used to capture the injected bunches from injector SSC (or SFC) and to accumulate the beam to high intensity by RF stacking method. In the present paper, the designed RF parameters and the details of hardware for the RF system are described.

  15. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

  16. A fast solver for systems of axisymmetric ring vortices

    NASA Astrophysics Data System (ADS)

    Strickland, James H.; Amos, Donald E.

    1990-09-01

    A method which is capable of efficient calculation of the axisymmetric flow field produced by a large system of ring vortices is presented in this report. The system of ring vortices can, in turn, be used to model body surfaces and wakes in incompressible unsteady axisymmetric flow fields. This method takes advantage of source point and field point series expansions which enables one to make calculations for interactions between groups of vortices which are in well separated spatial domains rather than having to consider interactions between every pair of vortices. In this work, series expansions for the stream function of the ring vortex system are obtained. Such expansions explicitly contain the radial and axial velocity components. A FORTRAN computer code RSOLV has been written to execute the fast solution technique to calculate the stream function and the axial and radial velocity components at points in the flow field. Test cases have been run to optimize the code and to benchmark the truncation errors and CPU time savings associated with the method. Non-dimensional truncation errors for the stream function and total velocity field are on the order of 5 times 10(exp -5) and 3 times 10(exp -3) respectively. Single precision accuracy produces errors in these quantities up to about 1 times 10(exp -5). For 100 vortices in the field, there is virtually no CPU time savings with the fast solver. For 10,000 vortices in the flow, the fast solver obtains solutions in about 1 to 3 percent of the time required for the direct solution technique. Simulations of vortices with square and circular cores were run in order to obtain expressions for the self-induced velocities of such vortices.

  17. Status of NSLS-II Storage Ring Vacuum Systems

    SciTech Connect

    Doom,L.; Hseuh,H.; Ferreira, M.; Longo, C.; Ravindranath, V.; Settepani, P.; Sharma, S.; Wilson, K.

    2009-05-04

    National Synchrotron Light Source II (NSLS-II), being constructed at Brookhaven National Laboratory, is a 3-GeV, high-flux and high- brightness synchrotron radiation facility with a nominal current of 500 mA. The storage ring vacuum system will have extruded aluminium chambers with ante-chamber for photon fans and distributed NEG strip pumping. Discrete photon absorbers will be used to intercept the un-used bending magnet radiation. In-situ bakeout will be implemented to achieve fast conditioning during initial commissioning and after interventions.

  18. High resolution upgrade of the ATF damping ring BPM system

    SciTech Connect

    Terunuma, N.; Urakawa, J.; Frisch, J.; May, J.; McCormick, D.; Nelson, J.; Seryi, A.; Smith, T.; Woodley, M.; Briegel, C.; Dysert, R.; /Fermilab

    2008-05-01

    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished in its first stage, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, and also tests a new automatic gain error correction schema. The technical concept and realization, as well as preliminary results of beam studies are presented.

  19. Exogenous dust delivery into the Saturnian system and the age of Saturn's rings

    NASA Astrophysics Data System (ADS)

    Kempf, S.; Horanyi, M.; Srama, R.; Altobelli, N.

    2015-10-01

    Even 450 years after Galileo Galilei's discovery of Saturn's rings, their origin and evolution is still not known. The rings are the brightest of the four ring systems of the solar system and have at least the mass of the moon Mimas[?]. Interactions with Saturn's moons and viscous spreading of the ring material seem to imply a ring age of about a tenth of the age of the Saturnian system of about 4.5 billion years[?, ?]. A young ring age is problematic because the disruption of a Mimas-sized body or a comet in the Roche zone of Saturn would result in a ring with a much larger rock content than observed today[?, ?, ?]. The unique ring color resulting mainly from the pollution of the ring material with interplanetary meteoroids provides a key for constraining the ring age[?, ?, ?]. Here we report on the first direct measurements of the meteoroid flux into the Saturnian system byCassini's Cosmic Dust Analyzer (CDA).We measured the impact speed vectors of 133 extrinsic micrometeoroids # 2μm and determined their orbital elements. We determined the mass flux into the Saturnian system to be 10-18kg/m2s. This finding suggest a ring exposure time of 4.5 billion years and is in support of an early ring generation from a proto-Titan during the formation of the Saturnian system[?].

  20. O-ring sealing arrangements for ultra-high vacuum systems

    SciTech Connect

    Flaherty, R.; Kim, C.

    1981-08-04

    An all metal reusable o-ring sealing arrangement is disclosed for sealing two concentric tubes in an ultra-high vacuum system. An o-ring of a heat recoverable alloy such as nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The o-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the o-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  1. O-Ring sealing arrangements for ultra-high vacuum systems

    DOEpatents

    Kim, Chang-Kyo; Flaherty, Robert

    1981-01-01

    An all metal reusable O-ring sealing arrangement for sealing two concentric tubes in an ultra-high vacuum system. An O-ring of a heat recoverable alloy such as Nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The O-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the O-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  2. Klystron 'efficiency loop' for the ALS storage ring RF system

    SciTech Connect

    Kwiatkowski, Slawomir; Julian, Jim; Baptiste, Kenneth

    2002-05-20

    The recent energy crisis in California has led us to investigate the high power RF systems at the Advanced Light Source (ALS) in order to decrease the energy consumption and power costs. We found the Storage Ring Klystron Power Amplifier system operating as designed but with significant power waste. A simple proportional-integrator (PI) analog loop, which controls the klystron collector beam current, as a function of the output RF power, has been designed and installed. The design considerations, besides efficiency improvement, were to interface to the existing system without major expense. They were to also avoid the klystron cathode power supply filter's resonance in the loop's dynamics, and prevent a conflict with the existing Cavity RF Amplitude Loop dynamics. This efficiency loop will allow us to save up to 700 MW-hours of electrical energy per year and increase the lifetime of the klystron.

  3. Fast solver for systems of axisymmetric ring vortices

    NASA Astrophysics Data System (ADS)

    Strickland, James H.; Amos, Donald E.

    1992-03-01

    A method that is capable of efficient calculation of the axisymmetric flowfield produced by a large system of ring vortices is presented in this paper. The system of ring vortices can, in turn, be used to model body surfaces and wakes in incompressible unsteady axisymmetric flowfields. This method takes advantage of source-point and field-point series expansion, which enables one to make calculations for interactions between groups of vortices that are in well-separated spatial domains rather than having to consider interactions between every pair of vortices. A FORTRAN computer code, RSOLV, has been written to execute the fast solution technique. For 100 vortices in the field, there is virtually no CPU time savings with the fast solver. For 10,000 vortices in the flow, the fast solver obtains solutions in about 1-3 percent of the time required for the direct solution technique. Formulas for the self-induced velocity of discretized regions of the flowfield have been developed. Use of these formulas allows correct convection of discretized patches of vorticity in the flowfiled.

  4. TRANSIT MODEL OF PLANETS WITH MOON AND RING SYSTEMS

    SciTech Connect

    Tusnski, Luis Ricardo M.; Valio, Adriana E-mail: avalio@craam.mackenzie.br

    2011-12-10

    Since the discovery of the first exoplanets, those most adequate for life to begin and evolve have been sought. Due to observational bias, however, most of the discovered planets so far are gas giants, precluding their habitability. However, if these hot Jupiters are located in the habitable zones of their host stars, and if rocky moons orbit them, then these moons may be habitable. In this work, we present a model for planetary transit simulation considering the presence of moons and planetary rings around a planet. The moon's orbit is considered to be circular and coplanar with the planetary orbit. The other physical and orbital parameters of the star, planet, moon, and rings can be adjusted in each simulation. It is possible to simulate as many successive transits as desired. Since the presence of spots on the surface of the star may produce a signal similar to that of the presence of a moon, our model also allows for the inclusion of starspots. The result of the simulation is a light curve with a planetary transit. White noise may also be added to the light curves to produce curves similar to those obtained by the CoRoT and Kepler space telescopes. The goal is to determine the criteria for detectability of moons and/or ring systems using photometry. The results show that it is possible to detect moons with radii as little as 1.3 R{sub Circled-Plus} with CoRoT and 0.3 R{sub Circled-Plus} with Kepler.

  5. Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring

    NASA Technical Reports Server (NTRS)

    Lewis, James L. (Inventor); Carroll, Monty B. (Inventor); Morales, Ray H. (Inventor); Le, Thang D. (Inventor)

    2002-01-01

    The present invention relates to a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring. The docking system of the present invention preferably comprises two Docking- assemblies, each docking assembly comprising a load sensing ring having an outer face, one of more electromagnets, one or more load cells coupled to said load sensing ring. The docking assembly further comprises a plurality of actuator arms coupled to said load sensing ring and capable of dynamically adjusting the orientation of said load sensing ring and a reconfigurable closed loop control system capable of analyzing signals originating from said plurality of load cells and of outputting real time control for each of the actuators. The docking assembly of the present invention incorporates an active load sensing system to automatically dynamically adjust the load sensing ring during capture instead of requiring significant force to push and realign the ring.

  6. System of invariant correlation to rotation using a ring mask

    NASA Astrophysics Data System (ADS)

    Solorza, Selene; Álvarez-Borrego, Josué; Kober, Vitaly

    2008-08-01

    A new rotational invariance computational filter is presented. The filter was applied to a problem image, in this case, an image of 256 by 256 pixels of black background with a centered white Arial letter. The complete alphabet is represented in those images. The image is rotated one degree by one degree until complete 360 degrees; hence, for each alphabet letter we are generating 360 images. To achieve the rotational invariance, first of all, a translational invariance is applied and then a 256 by 256 binary mask of concentric circular rings of three pixels of thickness and separation is used. The sum of the information in the circular rings represents the signature of the image. The average of the signature of the 360 images of a selected letter is the filter used to compute the phase correlation with all alphabet letter and their rotated images. The confidence level is calculated by the mean value with two standard errors (2SE) of those 360 correlation values for each letter. The confidence level shows that this system works efficiently on the discrimination between letters.

  7. The Second Ring-Moon System of Uranus: Discovery and Dynamics

    NASA Technical Reports Server (NTRS)

    Showalter, M. R.; Lissauer, J. J.

    2005-01-01

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All orbit outside of Uranus's previously known (main) ring system, but interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely-packed, rapidly varying and possibly unstable dynamica1 system.

  8. The second ring-moon system of Uranus: discovery and dynamics.

    PubMed

    Showalter, Mark R; Lissauer, Jack J

    2006-02-17

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All of them orbit outside of Uranus's previously known (main) ring system but are interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely packed, rapidly varying, and possibly unstable dynamical system. PMID:16373533

  9. Saturn's F ring and shepherd satellites a natural outcome of satellite system formation

    NASA Astrophysics Data System (ADS)

    Hyodo, Ryuki; Ohtsuki, Keiji

    2015-09-01

    Saturn's F ring is a narrow ring of icy particles, located 3,400 km beyond the outer edge of the main ring system. Enigmatically, the F ring is accompanied on either side by two small satellites, Prometheus and Pandora, which are called shepherd satellites. The inner regular satellites of giant planets are thought to form by the accretion of particles from an ancient massive ring and subsequent outward migration. However, the origin of a system consisting of a narrow ring and shepherd satellites remains poorly understood. Here we present N-body numerical simulations to show that a collision of two of the small satellites that are thought to accumulate near the main ring's outer edge can produce a system similar to the F ring and its shepherd satellites. We find that if the two rubble-pile satellites have denser cores, such an impact results in only partial disruption of the satellites and the formation of a narrow ring of particles between two remnant satellites. Our simulations suggest that the seemingly unusual F ring system is a natural outcome at the final stage of the formation process of the ring-satellite system of giant planets.

  10. Photometric Analysis of the Jovian Ring System and Modeling of Ring Origin and Evolution

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.

    2003-01-01

    We have successfully completed the work described in our proposal. The work supported by this grant resulted in the publication of the following paper: Brooks, S. M., L. W. Esposito, M. R. Showalter, and H. B. Throop. 2002. The size distribution of Jupiter's main ring from Galileo imaging and spectroscopy. Icarus, in press. This was also the major part of Dr. Shawn Brooks PhD dissertation. Dr. Brooks gave oral presentations on this work at the Lunar and Planetary Conference, the annual meetings of the Division for Planetary Sciences of the American Astronomical Society, the annual meetings of the European Geophysical Society, the international Jupiter Conference in Boulder, the Jupiter after Galileo and Cassini Conference in Lisbon and to the Working Group in Non-Linear Dynamics in Potsdam, Germany. This work was reviewed in: Esposito, L. W. 2002. Planetary rings. Rep. hog. Phys. 65, 1741-1783. Planetary rings. LASP reprint 874. Online at http://stacks.iop.org/RoPP/65/1741. Dr. Esposito gave presentations at schools and over the internet on the results of this work. Dr. Brooks lectured in undergraduate and graduate classes on Jupiter's rings, and on the meaning of his research. In August 2003, Dr. Shawn Brooks received the Phd degree from the University of Colorado in Astrophysical and Planetary Sciences.

  11. Commissioning results of the APS storage ring diagnostics systems

    SciTech Connect

    Lumpkin, A.H.

    1996-12-31

    Initial commissionings of the Advanced Photon Source (APS) 7-GeV storage ring and its diagnostics systems have been done. Early studies involved single-bunch measurements for beam transverse size ({sigma}{sub x} {approx} 150 {mu}m, {sigma}{sub y} {approx} 50 {mu}m), current, injection losses, and bunch length. The diagnostics have been used in studies related to the detection of an extra contribution to beam jitter at {approximately} 6.5 Hz frequency; observation of bunch lengthening ({sigma} {approx} 30 to 60 ps) with single-bunch current; observation of an induced vertical, head-tail instability; and detection of a small orbit change with insertion device gap position. More recently, operations at 100-mA stored-beam current, the baseline design goal, have been achieved with the support of beam characterizations.

  12. Development of the orbit feedback system for the VSX ring

    NASA Astrophysics Data System (ADS)

    Satoh, M.; Harada, K.; Takaki, H.; Koseki, T.; Nakamura, N.; Kamiya, Y.; Hanawa, K.

    2001-07-01

    An orbit feedback system will be installed in the VSX ring to stabilize the photon beam. The new COD correction method, the eigenvector method with constraints, is adopted for calculation of the steering-magnet currents. A computer simulation shows that the new method can tightly fix the beam positions at insertion devices, correcting the whole closed orbit globally with almost the same performance as the ordinary eigenvector method. A test VME unit including DSP and shared memory boards is being developed for the fast feedback control and its performance test shows that the total feedback time is less than 1 ms (875 μs) except for the network and VME-bus transfer times related to the shared memory board.

  13. Arrayed Micro-Ring Spectrometer System and Method of Use

    NASA Technical Reports Server (NTRS)

    Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    A spectrometer system includes an array of micro-zone plates (MZP) each having coaxially-aligned ring gratings, a sample plate for supporting and illuminating a sample, and an array of photon detectors for measuring a spectral characteristic of the predetermined wavelength. The sample plate emits an evanescent wave in response to incident light, which excites molecules of the sample to thereby cause an emission of secondary photons. A method of detecting the intensity of a selected wavelength of incident light includes directing the incident light onto an array of MZP, diffracting a selected wavelength of the incident light onto a target focal point using the array of MZP, and detecting the intensity of the selected portion using an array of photon detectors. An electro-optic layer positioned adjacent to the array of MZP may be excited via an applied voltage to select the wavelength of the incident light.

  14. Results from a survey of the dynamics shaping Uranus' Mab/μ-ring system

    NASA Astrophysics Data System (ADS)

    Kumar, Kartik; de Pater, Imke; Showalter, Mark R.

    2014-11-01

    Based on Hubble Space Telescope (HST) data, Showalter and Lissauer (2006) reported the discovery of two faint rings beyond Uranus’ main rings: the ν- and μ- rings. They constitute Uranus' outer ring system and are located beyond the ɛ-ring but interior to the large classical moons. After co-adding a series of HST images, Showalter and Lissauer (2006) obtained radial profiles for both new rings. They discovered that the peak radial intensity of the μ-ring aligns closely with the orbit of Mab. Along with numerous other observations, this points to the fact that the Mab/μ-ring system is highly coupled.The discovery of the μ-ring has led to open questions about dust dynamics beyond Uranus' main rings. Like Saturn's E-ring, observations reveal that the μ-ring is blue, indicative of a pre-dominance of sub-micron-sized particles (de Pater et al., 2006). The E-ring results from plumes on Enceladus' south pole, however the origin of the μ-ring remains a mystery. The latter is likely fed by ejecta from micro-meteorite impacts with Mab, much like Jupiter's faint rings are regenerated by companion (small) moons (Burns et al., 1999). The μ-ring's steep size-distribution suggests that there is an unknown mechanism at play that hides or removes large dust particles. We present results from an investigation into the forces shaping the μ-ring. To simulate the motion of dust in the Mab/μ-ring system, we developed a numerical toolbox (Dustsim; Kumar et al., 2015) that uses Tudat (Kumar et al., 2012). We performed integrations using Dustsim that included the effects of Uranus' gravity field, titled magnetic moment, solar radiation pressure, and collisions with a putative suite of large μ-ring bodies, hypothesized as the cause of Mab's anomalous orbital motion (Kumar et al., 2014). Following on from previous studies (e.g., Sfair and Giuliatti Winter, 2009; Sfair and Giuliatti Winter, 2012), we present a survey of the expected lifetime of μ-ring dust, as a function of

  15. Near-infrared spectra of the uranian ring system

    NASA Astrophysics Data System (ADS)

    de Kleer, Katherine; de Pater, Imke; Ádámkovics, Máté; Hammel, Heidi

    2013-09-01

    We present the first high-resolution near-infrared (1.18-2.38 μm) spectrum of the rings of Uranus, as observed with adaptive optics on the W.M. Keck II telescope in August 2010. We derive ring equivalent widths, as well as ring and particle reflectivities for the ɛ ring and ringlet groups based on H- and K-band data. We find the rings to be gray, indicating that they are dominated by large particles rather than dust, and we find no evidence for water ice. We present a reflectivity spectrum for the ɛ ring alone, which we also find to be consistent with a flat spectrum. We derive H-band ring particle reflectivities of 0.022 ± 0.010, 0.051 ± 0.009 0.042 ± 0.012, and 0.043 ± 0.001 and K-band ring particle reflectivities of 0.016 ± 0.010, 0.034 ± 0.012, 0.047 ± 0.008 and 0.041 ± 0.002 for the 456, αβ, ηγδ, and ɛ ring groups. Previous observations have found ring particle reflectivities in the 0.033-0.044 range (de Pater, I., Gibbard, S., Macintosh, B.A., Roe, H.G. [2002]. Icarus 160, 359-374; Gibbard, S.G., de Pater, I., Hammel, H.B. [2005]. Icarus 174, 253-262), and are generally consistent with our results.

  16. An objective reference system for studying rings in the ocean

    NASA Astrophysics Data System (ADS)

    Castelão, Guilherme P.; Irber, Luiz C.; Villas Boas, Ana B. M.

    2013-12-01

    Rings are marine vortices with a scale of hundreds of kilometers that can last for months, whose associated transport and mixing play an important role in the ocean dynamics. Such features are traditionally treated as a geostrophic flow, but since the centrifugal acceleration is not negligible in the inner core, the cyclo-geostrophic balance is a better approximation for the rings. In the present work, we describe a novel objective technique to identify the ring center, which is used as the origin of a convenient framework to handle rings under the cyclo-geostrophic balance. Furthermore, we correct the velocity field by the translation to isolate the swirl movement, a procedure ignored by other methodologies. We show that the lack of such correction would lead to an error of 30 km on the center definition of a ship surveyed North Brazil Current Ring with 160 km of radius. Another distinct characteristic of our approach is the flexibility in the spatio-temporal structure of the data, because it allows for ungridded data, an important ability for in situ observations. That also enables the use of a hybrid dataset composed from different instruments. The error on the Monte Carlo experiments to identify the center of the propagating ring is less than 10 km, and depends on the level of noise, sampling strategy, and strength of the ring, among other factors. This technique was fully implemented in PyRings, an open Python library with a collection of procedures to handle oceanic rings and mesoscale eddies in general.

  17. Placement of the GaBP ring system in the banded gastric bypass operation.

    PubMed

    Fobi, Mathias A L

    2005-09-01

    Currently, bariatric surgeons fashion the band or ring reinforcement prosthesis, to control the stoma in the vertical banded gastroplasty and gastric bypass operations for morbid obesity. To meet this need, the GaBP Ring system has been developed in various sizes, and consists of 4 main parts to provide a means for inserting a ring around the gastric pouch in the banded gastric bypass or the vertical banded gastroplasty. The pre-manufactured and sterilized device provides for better standardization and quality control than individually surgeon-fashioned devices. The GaBP Ring system is described, and the technique of placement and the pertinent initial clinical results are presented. PMID:16197796

  18. Status of /hacek C/erenkov Ring Imaging systems

    SciTech Connect

    Leith, D.W.G.S.

    1987-06-01

    Cerenkov Ring Imaging is briefly introduced, and the problems or choices of designing such a counter are discussed. Recent results from the DELPHI and SLD prototype are presented and compared to the expected performances. 13 refs., 33 figs., 2 tabs.

  19. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  20. Multiple internal seal ring micro-electro-mechanical system vacuum packaging method

    NASA Technical Reports Server (NTRS)

    Hayworth, Ken J. (Inventor); Yee, Karl Y. (Inventor); Shcheglov, Kirill V. (Inventor); Bae, Youngsam (Inventor); Wiberg, Dean V. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum packaging method that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

  1. Ring lens focusing and push-pull tracking scheme for optical disk systems

    NASA Technical Reports Server (NTRS)

    Gerber, R.; Zambuto, J.; Erwin, J. K.; Mansuripur, M.

    1993-01-01

    An experimental comparison of the ring lens and the astigmatic techniques of generating focus-error-signal (FES) in optical disk systems reveals that the ring lens generates a FES over two times steeper than that produced by the astigmat. Partly due to this large slope and, in part, because of its diffraction-limited behavior, the ring lens scheme exhibits superior performance characteristics. In particular the undesirable signal known as 'feedthrough' (induced on the FES by track-crossings during the seek operation) is lower by a factor of six compared to that observed with the astigmatic method. The ring lens is easy to align and has reasonable tolerance for positioning errors.

  2. The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust

    SciTech Connect

    de Pater, I; Gibbard, S G; Hammel, H B

    2005-02-02

    We present a high quality image of the uranian ring system, obtained in July 2004 at 2.2 {micro}m with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first ground-based image of the ring 1986U2R, seen only once before by the Voyager spacecraft. We show that this ring extends inward to {approx} 7000 km above the Uranus cloud deck. Its VIF (total vertically integrated I/F) is {approx} 100 m. We further detected narrow sheets of dust in between the {delta} and {epsilon} rings, and in between rings 4 and {alpha}, with a VIF of 14 and 20 m, respectively. Surprisingly, we find that the particles in Uranus' 9 main rings are distributed within a mono-layer, rather than the usually adopted poly-layer model. We come to this conclusion via a comparison of the VIF as derived from our 2003 data at a ring opening angle B {approx} 18{sup o} (from Gibbard et al. 2004) with those derived in this paper at B {approx} 11{sup o}. We show that the VIF increases approximately as 1/sinB at the ring ansae, but is independent of sinB in front of the disk. This combination of factors can only be explained if the particles in Uranus' rings are distributed in a mono-layer, a configuration which makes the uranian system unique amongst the giant planets.

  3. Note: O-ring stack system for electron gun alignment.

    PubMed

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-01

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications. PMID:25638137

  4. Note: O-ring stack system for electron gun alignment

    NASA Astrophysics Data System (ADS)

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-01

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  5. Note: O-ring stack system for electron gun alignment

    SciTech Connect

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-15

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  6. Voyager Saturnian ring measurements and the early history of the solar system

    NASA Technical Reports Server (NTRS)

    Alfven, H.; Axnaes, I.; Brenning, N.; Lindquist, P. A.

    1985-01-01

    The mass distribution in the Saturnian ring system is investigated and compared with predictions from plasma cosmogony. According to this theory, the matter in the rings was once a magnetized plasma, in which gravitation is balanced by the centrifugal and electromagnetic forces. As the plasma is neutralized, the electromagnetic forces disappear and the matter falls in to 2/3 of the original saturnocentric distance. This causes the cosmogonic shadow effect, demonstrated for the large scale structure of the Saturnian ring system. It is shown that many structures of the present ring system can be understood as shadows and antishadows of cosmogonic origin. These appear in the form of double rings centered around a position a factor 0.64 (slightly 2/3) closer to Saturn than the causing feature. Voyager data agree with an accuracy 1%.

  7. Gaseous toroid around Saturn. [Saturnian ring system for atomic hydrogen trapping in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Mcdonough, T. R.

    1974-01-01

    The trapping of Titan's escaping atmosphere in the Saturnian system by a toroidal ring is discussed. The radius of the toroid is comparable to Titan's orbit, or about ten times larger than the visible rings. Theoretical atmospheric models are formulated that consider Saturn's gravitational attraction and magnetospheric properties in forming this toroid and in protecting toroid particles from direct ionization by solar wind particles.

  8. Convergent synthesis of the HIJKLM ring system of ciguatoxin CTX3C.

    PubMed

    Takamura, Hiroyoshi; Nishiuma, Naoki; Abe, Takashi; Kadota, Isao

    2011-09-01

    The HIJKLM ring system of ciguatoxin CTX3C was synthesized in a convergent manner. The key steps were a conjugate addition/alkylation sequence, spiroacetalization, intramolecular allylation, ring-closing metathesis, and hydrogenation to form the 36-α-methyl substituent. PMID:21805971

  9. The NICS-XY-scan: identification of local and global ring currents in multi-ring systems.

    PubMed

    Gershoni-Poranne, Renana; Stanger, Amnon

    2014-05-01

    Nucleus-independent chemical shift (NICS)-based methods are very popular for the determination of the induced magnetic field under an external magnetic field. These methods are used mostly (but not only) for the determination of the aromaticity and antiaromaticity of molecules and ions, both qualitatively and quantitatively. The ghost atom that serves as the NICS probe senses the induced magnetic field and reports it in the form of an NMR chemical shift. However, the source of the field cannot be determined by NICS. Thus, in a multi-ring system that may contain more than one induced current circuit (and therefore more than one source of the induced magnetic field) the NICS value may represent the sum of many induced magnetic fields. This may lead to wrong assignments of the aromaticity (and antiaromaticity) of the systems under study. In this paper, we present a NICS-based method for the determination of local and global ring currents in conjugated multi-ring systems. The method involves placing the NICS probes along the X axis, and if needed, along the Y axis, at a constant height above the system under study. Following the change in the induced field along these axes allows the identification of global and local induced currents. The best NICS type to use for these scans is NICSπZZ , but it is shown that at a height of 1.7 Å above the molecular plane, NICSZZ provides the same qualitative picture. This method, namely the NICS-XY-scan, gives information equivalent to that obtained through current density analysis methods, and in some cases, provides even more details. PMID:24677667

  10. Palladium-catalyzed arylation of 2H-chromene: a new entry to pyrano[2,3-c]carbazoles.

    PubMed

    Ranjith Reddy, K; Siva Reddy, A; Dhaked, Devendra K; Rasheed, S K; Pathania, Anup Singh; Shankar, Ravi; Malik, Fayaz; Das, Parthasarathi

    2015-09-21

    Pyrano[2,3-c]carbazoles which are biologically valuable and synthetically challenging frameworks are synthesized in high yields over five steps from commercially available resorcinol. Palladium-catalyzed arylation remains a key step in this novel strategy. The versatility of this protocol has been demonstrated by the synthesis of naturally occurring alkaloid clauraila C and 7-methoxyglycomaurin. The anti-proliferative activity of these designed compounds (5a, 5f, and 5l) has been evaluated in a cancer cell line (MOLT-4). The molecular docking study revealed that this pyrano[2,3-c]carbazole class of molecules selectively occupies the colchicine binding site of the tubulin-polymer. PMID:26235231

  11. Diaqua­bis­(2-oxo-2H-chromene-3-carboxyl­ato)copper(II)

    PubMed Central

    Cui, Yue; Gao, Qian; Wang, Huan-Huan; Wang, Lin; Xie, Ya-Bo

    2011-01-01

    In the title compound, [Cu(C10H5O4)2(H2O)2], the CuII atom lies on a crystallographic inversion center and exhibits an octa­hedral coordination defined by two O atoms from water mol­ecules in the axial positions and by four O atoms from two deprotonated coumarin-3-carb­oxy­lic acid ligands in the equatorial positions. The angles around the CuII atom vary between 85.32 (6) and 94.68 (6)°. The Cu—O bond distances between the CuII atom and the O atoms vary between 1.9424 (14) and 2.3229 (15) Å. The layers inter­digitate via face-to-face aromatic inter­actions [3.6490 (8) Å] between coumarin moieties such that the inter­layer separation is 10.460 (2) Å, i.e. the length of the c axis. O—H⋯O hydrogen bonds between the H atoms of coordinated water mol­ecules and the O atoms of carboxyl­ate groups link the complex mol­ecules into layers parallel to the ab plane. PMID:21754664

  12. Detecting ring systems around exoplanets using high resolution spectroscopy: the case of 51 Pegasi b

    NASA Astrophysics Data System (ADS)

    Santos, N. C.; Martins, J. H. C.; Boué, G.; Correia, A. C. M.; Oshagh, M.; Figueira, P.; Santerne, A.; Sousa, S. G.; Melo, C.; Montalto, M.; Boisse, I.; Ehrenreich, D.; Lovis, C.; Pepe, F.; Udry, S.; Garcia Munoz, A.

    2015-11-01

    Aims: In this paper we explore the possibility that the recently detected reflected light signal of 51 Peg b could be caused by a ring system around the planet. Methods: We use a simple model to compare the observed signal with the expected signal from a short-period giant planet with rings. We also use simple dynamical arguments to understand the possible geometry of such a system. Results: We provide evidence that, to a good approximation, the observations are compatible with the signal expected from a ringed planet, assuming that the rings are non-coplanar with the orbital plane. However, based on dynamical arguments, we also show that this configuration is unlikely. In the case of coplanar rings we then demonstrate that the incident flux on the ring surface is about 2% the value received by the planet, a value that renders the ring explanation unlikely. Conclusions: The results suggest that the signal observed cannot in principle be explained by a planet+ring system. We discuss, however, the possibility of using reflected light spectra to detect and characterize the presence of rings around short-period planets. Finally, we show that ring systems could have already been detected by photometric transit campaigns, but their signal could have been easily misinterpreted by the expected light curve of an eclipsing binary. Based on observations collected at ESO facilities under program 091.C-0271 (with the HARPS spectrograph at the ESO 3.6-m telescope, La Silla-Paranal Observatory).Appendices are available in electronic form at http://www.aanda.org

  13. 3-(4-Meth­oxy­benzo­yl)-6-nitro­coumarin

    PubMed Central

    Vazquez-Rodriguez, Saleta; Uriarte, Eugenio; Santana, Lourdes

    2013-01-01

    In the title coumarin derivative (also known as 2H-chromen-2-one or 2H-1-benzopyran-2-one), C17H11NO6, the coumarin ring system is nearly planar, with a dihedral angle of 3.35 (9)° between the pyrone and the benzene rings. The dihedral angle between the planes formed by the coumarin ring system and the benzene substituent is 54.60 (7)°, clearly showing the non-coplanarity of the whole aromatic system. The crystal studied was a non-merohedral twin; the minor component refined to approximately 0.44. PMID:23476538

  14. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.

    2002-08-01

    The past two decades have witnessed dramatic changes in our view and understanding of planetary rings. We now know that each of the giant planets in the Solar System possesses a complex and unique ring system. Recent studies have identified complex gravitational interactions between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting ring scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various ring systems, in the broadest context. Understanding the origin and age requires us to know the current ring properties, and to understand the dominant evolutionary processes and how they influence ring properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary rings. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary ring science.

  15. Equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    SciTech Connect

    Ip, W.; Mendis, D.A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents ot flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionosheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  16. On the equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    NASA Technical Reports Server (NTRS)

    Ip, W.-H.; Mendis, D. A.

    1983-01-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents to flow near the dawn and dusk terminators and close across the midlatitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionospheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  17. On the equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Mendis, D. A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents to flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionospheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  18. Feasibility study of shape memory alloy ring spring systems for self-centring seismic resisting devices

    NASA Astrophysics Data System (ADS)

    Fang, Cheng; Yam, Michael C. H.; Lam, Angus C. C.; Zhang, Yanyang

    2015-07-01

    Shape memory alloys (SMAs) have recently emerged as promising material candidates for structural seismic resisting purposes. Most of the existing SMA-based strategies, however, are based on the wire or rod form of SMAs, where issues such as gripping complexity and fracture may exist. This paper presents a proof-of-concept study on an innovative type of SMA-based self-centring system, namely, a superelastic SMA ring spring system. The proposed system includes a series of inner high-strength steel (HSS) rings and outer superelastic SMA rings stacked in alternation with mating taper faces, where the resisting load is provided by the wedging action which tends to expand the outer rings and concurrently to squeeze the inner rings. The superelastic effect of the SMA offers energy dissipation and a driving force for recentring, and the frictional effect over the taper face further contributes to the overall resisting load and energy dissipation. The feasibility of the new system is carefully examined via numerical studies considering the parameters of ring thickness, taper angle, and coefficient of friction. The key hysteretic responses, including resisting load, stiffness, stress distributions, source of residual deformation, energy dissipation, and equivalent viscous damping, are discussed in detail. The behaviour of the SMA ring springs is also studied via analytical models, and the analytical predictions are found to agree well with the numerical results. Finally, two practical applications of the new system, namely self-centring HS-SMA ring spring connections, and self-centring SMA ring spring dampers, are discussed via comprehensive numerical studies.

  19. Hydrodynamic optimization of trust ring pump and lubricating oil system for large hydroelectric units thrust bearing

    NASA Astrophysics Data System (ADS)

    Lai, X.; Lu, Z.; Zhang, X.; Yang, S.

    2014-03-01

    Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions form thrust bearing and operation conditions of hydro turbine generator unit. Because the oil circulating and cooling system with thrust-ring- pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump, additionally, the head and discharge are varying with the operation conditions of hydro-generator unit and characteristic of the oil circulating and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulating and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization of both the oil circulating and cooling system and thrust-ring-pump is purposed in this paper. Firstly, the head and discharge required at different conditions are decided by 1D flow numerical simulation of the oil circulating and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and discharge from the simulation. Thirdly, the flow passage geometry matching optimization between holes inside the thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulating and cooling system are collaborative hydrodynamic optimized with predicted head- discharge curve and the efficiency-discharge curve of thrust-ring-pump. The presented methodology has

  20. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    SciTech Connect

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-20

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to 'hop' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power ({>=}330 We at beginning of life) during the 10-year cruise and 1-year science mission ({approx}11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  1. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-01

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to ``hop'' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power (>=330 We at beginning of life) during the 10-year cruise and 1-year science mission (~11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  2. Submission of Earth-based ring occultation observations to the NASA planetary data system rings discipline node

    NASA Technical Reports Server (NTRS)

    French, Richard G.

    1993-01-01

    This is a technical report summarizing our progress in our program of contributing high quality Earth-based occultation observations to NASA's Planetary Data System (PDS) Rings Node. During our first year of funding, we selected five data sets for eventual inclusion in the PDS Rings Node. These were Uranus occultation observations obtained by the PI and co-workers from the IRTF of event stars U34 (26 April 1986), U1052 (5 May 1988), U65 (21 June 1990), U7872 (25 June 1991), and U7808 (28 June 1991). In our original proposal, we described four tasks: data sets to a common format; documentation of the occultation observations and associated calibrations; calculation of the occultation geometry for each event; establish prototype PDS templates. As discussed in our renewal proposal, submitted 8 June 1993, we have completed the first three tasks, and are working on the fourth. As an indication of our progress to date, we provide information about each of the data sets, their formats, the documentation, and the method used for reconstructing the occultation geometry.

  3. Solar system history as recorded in the Saturnian ring structure

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1983-01-01

    Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure, with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils, which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas, Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent.

  4. Voyager Saturnian ring measurements and the early history of the solar system

    NASA Technical Reports Server (NTRS)

    Alfven, H.; Axnas, I.; Brenning, N.; Lindqvist, P.-A.

    1986-01-01

    The mass distribution in the Saturnian ring system is investigated and compared with predictions from the plasma cosmogony. According to this theory, the matter in the rings has once been in the form of a magnetized plasma, in which the gravitation is balanced partly by the centrifugal force and partly by the electromagnetic forces. As the plasma is neutralized, the electromagnetic forces disappear and the matter can be shown to fall in to 2/3 of the original saturnocentric distance. This causes the so called 'cosmogonic shadow effect', which has been demonstrated earlier for the asteroidal belt and in the large scale structure of the Saturnian ring system. The relevance of the cosmogonic shadow effect is investigated for parts of the fine structures of the Saturnian ring system. It is shown that many structures of the present ring system can be understood as shadows and antishadows of cosmogonic origin. These appear in the form of double rings centered around a position a factor 0.64 (slightly less than 2/3) closer to Saturn than the causing feature. Voyager data agree with an accuracy better than 1 percent.

  5. Clumps and Temporal Changes in the Jovian Ring System as Viewed by New Horizons

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.; Cheng, A. F.; Weaver, H. A.; Stern, S. A.; Spencer, J. R.; Throop, H.; Birath, E. M.; Rose, D.; Moore, J. M.

    2007-10-01

    New Horizons obtained 400 ring images of the Jovian ring system using the Long Range Reconnaissance Imager (LORRI). This camera has a broad bandpass spanning wavelengths λ = 0.35 to 0.85 µm. The ring was imaged at phase angles 7°-159°. In addition, one sequence of near-IR spectra (λ = 1.25 to 2.5 µm) was obtained by the Linear Etalon Imaging Spectral Array (LEISA) for compositional studies. Two ring rotation movies during Jupiter approach were used to search for small moons embedded within the system. These bodies might serve as source bodies for the prevalent ring dust. No moons were detected down to a threshold of 500 m radius, suggesting a sharp cutoff in the population of inner Jovian moons below 8-km Adrastea. Although this search focused on the main Jovian ring, any 1-km moons from orbital radius r = 100,000 km to beyond the orbit of Amalthea (r = 181,000 km) should have been detected multiple times. More surprisingly, the ring revealed two clusters of tiny clumps, one pair and one set of three. These are definitively not moons because they have longitudinal extents of a few tenths of a degree. Separations between clumps are 2 to 4° but are not uniform. These clump families both orbit within a brightness peak just interior to the orbit of Adrastea, at r = 128,740 km. Their origin is unknown. They are not visible at high phase angles, indicating that they are composed primarily of larger "parent” bodies, not dust. They are definitely not related to a clump detected in Cassini images of the Jovian ring from December 2000, indicating that at least some ring clumps are transient. The large quadrant asymmetries reported in earlier images from Voyager and Galileo are completely absent in the new data.

  6. Analysis of a Triple Star System Occulted By Saturn’s Rings

    NASA Astrophysics Data System (ADS)

    Bratcher, Allison; Colwell, J. E.; Bolin, B.

    2012-10-01

    On January 4, 2012, the Ultraviolet Imaging Spectrograph aboard the Cassini Spacecraft observed Saturn’s rings as they occulted the triple star system, Iota Orionis. Remarkably, the brightest star was occulted by the moon Prometheus, and we provide the timing information of first and last contact for navigation purposes and a chord across the moon. The large separation of the individual stars projected in the ring plane makes it possible to measure the profiles of narrow features in the rings as they were occulted by each of the three stars. This occultation thus provides a unique opportunity to measure short-scale longitudinal variations in narrow ringlets with stellar occultation data that usually provide only a single longitudinal sample. Iota Orionis has a low elevation angle (B=1.4 degrees) above the plane of the rings, enhancing the sensitivity of the occultation (by a factor of 1/sin(B)=41) to the optically thin regions of the rings such as the C Ring and the Cassini Division as well as faint ringlets in the Encke gap. We distinguished the three signals by creating a model triple star signal using data from another occultation. We were able to identify several faint, narrow ringlets, including two in the Encke gap, occulted by two of the three stars and more prominent ringlets, such as the Huygens ringlet, in all three stellar light curves. We present the equivalent widths of these ringlets in the data from this triple star system and limits on ring variability over the azimuthal separation of the stars that ranges from 6000 km at the inner C ring to 200 km at the outer A ring.

  7. DESIGN AND DEVELOPMENT OF THE SNS RING VACUUM INSTRUMENTATION AND CONTROL SYSTEMS.

    SciTech Connect

    HSEUH,H.C.; SMART,L.A.; TANG,J.Y.

    2001-06-18

    BNL is undertaking the design, construction and commissioning of the Spallation Neutron Source (SNS) accumulator ring and the beam transport lines [l]. Ultrahigh vacuum of 10{sup {minus}9} Torr is required in the accumulator ring to minimize beam-gas ionization, a contributing factor to the e-p instability observed in a few high-intensity proton storage rings. All vacuum instrumentation must be capable of local and remote operation to achieve a reliable vacuum system, especially in this extremely high intensity accelerator. The design and development of the SNS ring vacuum instrumentation and control through the Experimental Physics and Industrial Control System (EPICS) distributed real-time software tools are presented.

  8. Coherent THz Synchrotron Radiation from a Storage Ring with High-Frequency RF System

    NASA Astrophysics Data System (ADS)

    Wang, F.; Cheever, D.; Farkhondeh, M.; Franklin, W.; Ihloff, E.; van der Laan, J.; McAllister, B.; Milner, R.; Tschalaer, C.; Wang, D.; Wang, D. F.; Zolfaghari, A.; Zwart, T.; Carr, G. L.; Podobedov, B.; Sannibale, F.

    2006-02-01

    The generation of brilliant, stable, and broadband coherent synchrotron radiation (CSR) in electron storage rings depends strongly on ring rf system properties such as frequency and gap voltage. We have observed intense coherent radiation at frequencies approaching the THz regime produced by the MIT-Bates South Hall Ring, which employs a high-frequency S-band rf system. The measured CSR spectral intensity enhancement with 2 mA stored current was up to 10 000 times above background for wave numbers near 3cm-1. The measurements also uncovered strong beam instabilities that must be suppressed if such a very high rf frequency electron storage ring is to become a viable coherent THz source.

  9. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  10. Ring retroreflector system consisting of cube-corner reflectors with special coating

    SciTech Connect

    Burmistrov, V B; Sadovnikov, M A; Sokolov, A L; Shargorodskiy, V D

    2013-09-30

    The ring retroreflector system (RS) consisting of cubecorner reflectors (CCRs) with a special coating of reflecting surfaces, intended for uniaxially Earth-oriented navigation satellites, is considered. The error of distance measurement caused by both the laser pulse delay in the CCR and its spatial position (CCR configuration) is studied. It is shown that the ring RS, formed by the CCR with a double-spot radiation pattern, allows the distance measurement error to be essentially reduced. (nanogradient dielectric coatings and metamaterials)

  11. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    PubMed

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function. PMID:27420523

  12. Ring formation in the quasi-two-dimensional system of the patchy magnetic spheres

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng-yu; Jian, Xing-liang; Lu, Wei

    2016-04-01

    Fabricating new functional materials has always been at the center of colloidal science, and how to form circular rings is a meaningful challenge due to their special electronic, magnetic and optical properties. Magnetic colloidal spheres can self-assemble into rings, but these rings have an uncontrollable length and shape and also have to coexist with chains and defected clusters. To make the most of magnetic spheres being able to self-assemble into rings, a patch is added to the surface of the sphere to form a chiral link between particles. The structural transition in the system of patchy magnetic spheres is studied using the Monte Carlo simulation. When the patch angle is in the interval {{60}{^\\circ}} to {{75}{^\\circ}} , rings become the dominant structure if the strength of patchy interaction exceeds a particular threshold and the shape of these rings is close to the circle. With an increase in the patch angle, the threshold of patchy interaction decreases and the average length of the circular ring increases approximately from 5 to 8.5.

  13. The demise of Phobos and development of a Martian ring system

    NASA Astrophysics Data System (ADS)

    Black, Benjamin A.; Mittal, Tushar

    2015-12-01

    All of the gas giants in our Solar System host ring systems, in contrast to the inner planets. One proposed mechanism of planetary ring formation is disruption or mass shedding of moons. The orbit of Phobos, the larger of Mars's two moonlets, is gradually spiralling inwards towards Mars and the moon is experiencing increasing tidal stresses. Eventually, Phobos will either break apart to form a ring or it will crash into Mars. We evaluate these outcomes based on geologic, spectral and theoretical constraints, in conjunction with a geotechnical model that helps us determine the strength of Phobos. Our analysis suggests that much of Phobos is composed of weak, heavily damaged materials. We suggest that--with continued inward migration of the moon--the weakest material will disperse tidally in 20 to 40 million years to form a Martian ring. We predict that this ring will persist for 106 to 108 years and will initially have a comparable mass density to that of Saturn's rings. Any large fragment of Phobos that is strong enough to escape tidal breakup will eventually collide with Mars in an oblique, low-velocity impact. Our analysis of the evolution of Phobos underscores the potential orbital and topographic consequences of the growth and self-destruction of other inwardly migrating moons, including those that met their demise early in our Solar System's history.

  14. Performance of a two mirror, four reflection, ring field imaging system

    SciTech Connect

    Sommargren, G.E.

    1995-01-25

    The surface figure of the individual mirrors of a two mirror, four reflection, ring field imaging system has been measured after each phase of the construction process: substrate fabrication, coating and potting. Contributions to the final system wavefront error and performance of the system in terms of the modulation transfer function and initial imaging tests are discussed.

  15. The stability of the oscillation motion of charged grains in the Saturnian ring system

    NASA Astrophysics Data System (ADS)

    Xu, R.-L.; Houpis, L. F.

    1985-02-01

    A perturbation approach for the gravitoelectrodynamic forces encountered in the corotating plasma environment of Saturn is used to determine the stability of charged grains, given a random initial velocity. Attention is given to the implications of the Northrop and Hill (1982) and Mendis et al. (1982) results for the formation of the Saturnian ring system, and it is suggested that the marginal z stability radius at 1.5245 Saturn radii for Kepler-launched particles is due to an erosion process with ejecta of the order 0.05-0.5 microns, rather than that of the previously suggested plasma. The diffuseness of the Saturnian rings beyond the F ring is also explained in terms of instability, while a new critical radius for r instability is suggestd for the optical depth feature at 1.72 Saturn radii. The F ring is analyzed in detail.

  16. Phase-locked servo system. [for synchronizing the rotation of slip ring assembly

    NASA Technical Reports Server (NTRS)

    Burdin, C. (Inventor)

    1974-01-01

    A phase lock servo system is described for synchronizing the rotation of a slip ring assembly with the rotation of an air bearing table so that a minimum of torque will be imparted through cables extending from the slip ring assembly to the air bearing table as such is rotated. The system includes two servo loops. The first servo loop includes a rate gyroscope carried on the air bearing table which generates a signal through a summing junction to be compared with a signal coming from a tachometer coupled to the slip ring assembly. The corrective signal is applied to a torque motor for rotating the slip ring assembly. The second servo loop includes a pair of photo detector cells which generate pulses responsive to the rotation of the air bearing table and slip ring assembly which are fed through a phase detector, and a variable gain amplifier to the summing junction circuit to provide a fine adjustment for rotating the slip ring assembly.

  17. Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

    SciTech Connect

    Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei; Morozov, Vasiliy; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2015-09-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

  18. A pinger system for the Los Alamos Proton Storage Ring

    SciTech Connect

    Hardek, T.W.; Thiessen, H.A.

    1991-01-01

    Developers at the Proton Storage Ring have long desired a modulator and electrode combination capable of kicking the 800-MeV proton beam enough to conduct tune measurements with full intensity beams. At present this has been accomplished by reducing the voltage on one extraction kicker modulator and turning the other off. This method requires that all of the accumulated beam be lost on the walls of the vacuum chamber. In addition to tune measurements a more recent desire is to sweep out beam that may have leaked into the area between bunches. A four-meter electrode has been designed and constructed for the purpose. The design is flexible in that the electrode may be split in the center and rotated in order to provide vertical and horizontal electrodes each 2 meters long. In addition two solid-state pulse modulators that can provide 10kV in burst mode at up to 700 KHz have been purchased. This hardware and its intended use are described. 3 refs., 2 figs., 1 tab.

  19. Auto-production of biosurfactants reverses the coffee ring effect in a bacterial system

    NASA Astrophysics Data System (ADS)

    Sempels, Wouter; de Dier, Raf; Mizuno, Hideaki; Hofkens, Johan; Vermant, Jan

    2013-04-01

    The deposition of material at the edge of evaporating droplets, known as the ‘coffee ring effect’, is caused by a radially outward capillary flow. This phenomenon is common to a wide array of systems including colloidal and bacterial systems. The role of surfactants in counteracting these coffee ring depositions is related to the occurrence of local vortices known as Marangoni eddies. Here we show that these swirling flows are universal, and not only lead to a uniform deposition of colloids but also occur in living bacterial systems. Experiments on Pseudomonas aeruginosa suggest that the auto-production of biosurfactants has an essential role in creating a homogeneous deposition of the bacteria upon drying. Moreover, at biologically relevant conditions, intricate time-dependent flows are observed in addition to the vortex regime, which are also effective in reversing the coffee ring effect at even lower surfactant concentrations.

  20. Plasma effects in the formation, evolution and present configuration of the Saturnian ring system

    NASA Astrophysics Data System (ADS)

    Alfven, H.; Mendis, D. A.

    The Voyager 1 and 2 observations of the fine structure of the Saturnian ring system demonstrate the importance of electric forces in controlling the dynamics of fine (charged) dust in the rings. A new theory ('gravito-electrodynamics') which combines the electric and the gravitational forces on these grains leads to natural explanations of a number of observed ring phenomena. If plasma processes play a significant role in the dynamics of the ring system at the present time, it is difficult to avoid the conclusion that they also played an important and perhaps crucial role at cosmogonic times during the emplacement and subsequent condensation of the initial dusty plasma. It is suggested that the Saturnian ring system represents a 'time-capsule' containing vital clues about the physical processes operating during the early stages of its formation. It is shown that both its overall structure as well as its fine structure, as determined by Voyagers 1 and 2, indicate the crucial importance of plasma processes in its formation and subsequent evolution.

  1. Configuration maintaining control of three-body ring tethered system based on thrust compensation

    NASA Astrophysics Data System (ADS)

    Huang, Panfeng; Liu, Binbin; Zhang, Fan

    2016-06-01

    Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

  2. The Nucleolar Channel System of Human Endometrium Is Related to Endoplasmic Reticulum and R-Rings

    PubMed Central

    Kittur, Nupur; Zapantis, Gregory; Aubuchon, Mira; Santoro, Nanette; Bazett-Jones, David P.

    2007-01-01

    The nucleolar channel system (NCS) is a well-established ultrastructural hallmark of the postovulation endometrium. Its transient presence has been associated with human fertility. Nevertheless, the biogenesis, composition, and function of these intranuclear membrane cisternae are unknown. Membrane systems with a striking ultrastructural resemblance to the NCS, termed R-rings, are induced in nuclei of tissue culture cells by overexpression of the central repeat domain of the nucleolar protein Nopp140. Here we provide a first molecular characterization of the NCS and compare the biogenesis of these two enigmatic organelles. Like the R-rings, the NCS consists of endoplasmic reticulum harboring the marker glucose-6-phosphatase. R-ring formation initiates at the nuclear envelope, apparently by a calcium-mediated Nopp140-membrane interaction, as supported by the calcium-binding ability of Nopp140, the inhibition of R-ring formation by calcium chelators, and the concentration of Nopp140 and complexed calcium in R-rings. Although biogenesis of the NCS may initiate similarly, the reduced presence of complexed calcium and Nopp140 suggests the involvement of additional factors. PMID:17429075

  3. An analog RF gap voltage regulation system for the Advanced Photon Source storage ring.

    SciTech Connect

    Horan, D.

    1999-04-13

    An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control and permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands.

  4. The SLS Storage Ring Vertical Position Monitoring System

    SciTech Connect

    Zelenika, Sasa

    2004-05-12

    The goal of monitoring the vertical position of the SLS machine was achieved by employing a capacitive gauge-based Hydrostatic Leveling System (HLS). Although all the preliminary results showed that the aimed HLS micrometric range resolutions and accuracies have been reached, the long-time behavior of the system revealed considerable drifts. A satisfactory solution could eventually be reached only by adding to the working fluid a fungicide.

  5. Transverse beam feedback system for PLS storage ring

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Park, M. K.; Kim, D. T.; Kang, H. S.; Hwang, W. H.; Nam, S. H.

    2001-07-01

    As the stored beam current increases over 240 mA, transverse coupled-beam instability limits higher beam current in Pohang Light Source. A bunch by bunch transverse feedback system has been developed to cure these beam instabilities. It consists of beam oscillation detectors, betatron phase adjuster, power amplifiers and a stripline kicker. Design of each circuit and its functions are described with simple trigonometric equations. The result of the beam test has shown more than 30 dB damping of the beam oscillation in the full bandwidth of the system.

  6. Fiber optic self healing ring for power system communications

    SciTech Connect

    Phillippe, T.A.

    1995-12-31

    A 138kv system, consisting of ten transmission lines and eight substations were upgraded with a new communications system to improve the monitoring, protection and control functions, as well as to eliminate the requirements for leased lines from the telephone companies. Fiber optic communications were chosen to take advantage of fiber`s immunity to noise, large bandwidth capability, flexibility, and other characteristics. SONET transmission equipment was chosen to take advantage of the newest technology available, and to allow maximum capability for future expansion.

  7. Generation of dissipative temporal solitons in ring self-oscillating systems with amplifier klystrons

    NASA Astrophysics Data System (ADS)

    Grishin, S. V.; Dmitriev, B. S.; Skorokhodov, V. N.; Sharaevskii, Yu. P.

    2015-09-01

    Theoretical and experimental results are presented that show the possibility of forming periodic pulsed signal sequences with a profile similar to that of bright solitons in a ring self-oscillating system with an amplifier klystron. The generated pulse sequences are dissipative temporal solitons formed in the ring due to the establishment of balance both between gain and loss and between time dispersion and cubic nonlinearity of the klystron. Analytical solutions have been obtained for a generator model with a two-cavity amplifier klystron and an additional cavity resonator, which confirm the possibility of forming these dissipative structures.

  8. Tree ring records capture long-term memory in climate systems

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-03-01

    Measuring tree rings is a mainstay technique for estimating ancient climatic conditions, with a tree's year-by-year growth reflecting changes in precipitation and temperature. In some cases, paleoclimatological records compiled from tree ring measurements can stretch for thousands of years. Based on recent research, climatologists have found that hydrological and other systems have long-term memory. Drawing on tree ring measurements compiled from across the continental United States, Bowers et al. sought to determine whether such long-term relationships are preserved in ring width measurements. The authors analyzed the Hurst parameter—a measure of long-term memory—of 697 different tree ring records that were collected from 10 tree species from locations across the United States. They found that though each tree species had a different mean value for its Hurst parameter, meaning that each species recorded long-term trends in the climate differently, they all fell within the range suggestive of their being able to properly represent long-term memory.

  9. O-ring tube fittings form leakproof seal in hydraulic systems

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Leakproof fittings for hydraulic systems are designed to be welded to the ends of the tubing to be joined and mated to form a seal with one o-ring at the joint. Since the fittings are coupled at only one joint, they tend to be more reliable than standard fittings coupled at two joints.

  10. Diverse N-Heterocyclic Ring Systems via Aza-Heck Cyclizations of N-(Pentafluorobenzoyloxy)sulfonamides.

    PubMed

    Hazelden, Ian R; Ma, Xiaofeng; Langer, Thomas; Bower, John F

    2016-09-01

    Aza-Heck cyclizations initiated by oxidative addition of Pd(0) -catalysts into the N-O bond of N-(pentafluoro-benzoyloxy)sulfonamides are described. These studies, which encompass only the second class of aza-Heck reaction developed to date, provide direct access to diverse N-heterocyclic ring systems. PMID:27460965

  11. A betatron tune measurement system based on bunch-by-bunch transverse feedback at the Duke storage ring

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Z. Wu, W.; Li, Jing-Yi; He, Duo-Hui; K. Wu, Y.

    2013-07-01

    To combat electron beam instabilities, a digital bunch-by-bunch transverse feedback (TFB) system has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multibunch operation, the TFB system has not been needed for typical operation of the Duke storage ring. To explore the great potential of this system, we have developed beam diagnostic techniques using the TFB, in particular, the TFB based tune measurement techniques. The tune measurement technique allows us to conduct fast chromaticity measurements, compared with the existing chromaticity measurement system using a network analyzer. This new tune measurement system also enables us to measure the bunch tune for multibunch operation of the Duke storage ring. With the TFB based tune measurement system, we have studied the tune stability of the electron beam in the Duke storage ring. This tune system has also been used to calibrate the tune knob for the Duke storage ring.

  12. Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Pinilla-Alonso, N.; Ortiz, J. L.; Alvarez-Candal, A.; Sicardy, B.; Santos-Sanz, P.; Morales, N.; Colazo, C.; Fernández-Valenzuela, E.; Braga-Ribas, F.

    2014-08-01

    Context. A stellar occultation observed on 3rd June 2013 revealed the presence of two dense and narrow rings separated by a small gap around the Centaur object (10 199) Chariklo. The composition of these rings is not known. We suspect that water ice is present in the rings, as is the case for Saturn and other rings around the giant planets. Aims: In this work, we aim to determine if the variability in the absolute magnitude of Chariklo and the temporal variation of the spectral ice feature, even when it disappeared in 2007, can be explained by an icy ring system whose aspect angle changes with time. Methods: We explained the variations on the absolute magnitude of Chariklo and its ring by modeling the light reflected by a system as the one described above. Using X-shooter at VLT, we obtained a new reflectance spectra. We compared this new set of data with the ones available in the literature. We showed how the water ice feature is visible in 2013 in accordance with the ring configuration, which had an opening angle of nearly 34° in 2013. Finally, we also used models of light scattering to fit the visible and near-infrared spectra that shows different characteristics to obtain information on the composition of Chariklo and its rings. Results: We showed that absolute photometry of Chariklo from the literature and new photometric data that we obtained in 2013 can be explained by a ring of particles whose opening angle changes as a function of time. We used the two possible pole solutions for the ring system and found that only one of them, α = 151.30 ± 0.5, δ = 41.48 ± 0.2° (λ = 137.9 ± 0.5, β = 27.7 ± 0.2°), provides the right variation of the aspect angle with time to explain the photometry, whereas the other possible pole solution fails to explain the photometry. From spectral modeling, we derived the composition of the Chariklo surface and that of the rings using the result on the pole solution. Chariklo surface is composed with about 60% of amorphous

  13. Tissue culture system using a PANDA ring resonator and wavelength router for hydroponic plant.

    PubMed

    Kamoldilok, Surachart; Suwanpayak, Nathaporn; Suttirak, Saisudawan; Yupapin, Preecha P

    2012-06-01

    A novel system of nanofluidics trapping and delivery, which is known as a tissue culture system is proposed. By using the intense optical pulse(i.e., a soliton pulse) and a system constructed by a liquid core waveguide, the optical vortices (gradient optical fields/wells) can be generated, where the trapping tools in the same way as the optical tweezers in the PANDA ring resonator can be formed. By controlling the suitable parameters, the intense optical vortices can be generated within the PANDA ring resonator, in which the nanofluidics can be trapped and moved (transported) dynamically within the Tissue culture system(a wavelength router), which can be used for tissue culture and delivery in the hydroponic plant system. PMID:22411055

  14. An innovative seismic bracing system based on a superelastic shape memory alloy ring

    NASA Astrophysics Data System (ADS)

    Gao, Nan; Jeon, Jong-Su; Hodgson, Darel E.; DesRoches, Reginald

    2016-05-01

    Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system.

  15. Stability Analysis of a Turbocharger Rotor System Supported on Floating Ring Bearings

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Shi, Z. Q.; Zhen, D.; Gu, F. S.; Ball, A. D.

    2012-05-01

    The stability of a turbocharger rotor is governed by the coupling of rotor dynamics and fluid dynamics because the high speed rotor system is supported on a pair of hydrodynamic floating ring bearings which comprise of inner and outer fluid films in series. In order to investigate the stability, this paper has developed a finite element model of the rotor system with consideration of such exciting forces as rotor imbalance, hydrodynamic fluid forces, lubricant feed pressure and dead weight. The dimensionless analytical expression of nonlinear oil film forces in floating ring bearings have been derived on the basis of short bearing theory. Based on numerical simulation, the effects of rotor imbalance, lubricant viscosity, lubricant feed pressure and bearing clearances on the stability of turbocharger rotor system have been studied. The disciplines of the stability of two films and dynamic performances of rotor system have been provided.

  16. New photochromic pigments for interactive papers

    NASA Astrophysics Data System (ADS)

    Guglielmetti, R.

    1997-08-01

    2H-1-Benzopyrans (or 2H-Chromenes) are an important family of oxygenated heterocycles particularly attractive because of their photochromic properties. Indeed, 2H-Chromenes undergo a reversible ring opening of the pyran cycle. The Csp3-O-bond is cleaved by UV irradiation leading to opened colored forms (generally called 'photomerocyanines'). The opened isomer reverts to its original form via a thermal pathway. The first described chromenes, 2,2-dimethyl [2H]-chromenes and their benzo annulated derivatives (naphthopyrans) showed photochromic behavior only at low temperatures and, moreover led to undesirable by-products. Interest in research in this field was developed only recently because of the industrial applications of materials undergoing variable optical transmission of light. For this purpose the desirable properties could be summarized as follows: light efficiency for coloring in the near ultra violet region, low quantum yield for bleaching with visible light and fast thermal fading at ambient temperatures. Another important criterium concerns the good resistance to the fatigue under continuous irradiation. These kinds of requirements have led to several structural modifications in the chromene series. Particularly, improvement of photochromic properties ('colorability') was obtained by the annulation of the chromene ring in the 7,8 positions, by appropriate substitution of the naphthopyran cycle replacing the alkyl groups on the Csp3 carbon atom by cyclopropyl groups, spiro adamantyl groups, and overall, by aryl groups. This last kind of substitution is nearly indespensible for showing good photochromic properties. Our interest in benzopyran chemistry has been focused on the design and study of heterocyclo-fused analogues, in order to modify the photochromic parameters. So we have introduced five-ringed and six-ringed heterocyclic systems involving oxygen, sulphur and nitrogen heteroatoms, particularly with an annulation in 5,6 positions. The general

  17. Formation of regular satellites from ancient massive rings in the solar system.

    PubMed

    Crida, A; Charnoz, S

    2012-11-30

    When a planetary tidal disk--like Saturn's rings--spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn's, Uranus', and Neptune's satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems. PMID:23197530

  18. Controllable multiple-quantum transitions in a T-shaped small quantum dot-ring system

    NASA Astrophysics Data System (ADS)

    Chen, Xiongwen; Chen, Baoju; Song, Kehui; Zhou, Guanghui

    2016-05-01

    Based on the tight-binding model and the slave boson mean field approximation, we investigate the electron transport properties in a small quantum dot (QD)-ring system. Namely, a strongly correlated QD not only attaches directly to two normal metallic electrodes, but also forms a magnetic control Aharonov-Bohm quantum ring with a few noninteracting QDs. We show that the parity effect, the Kondo effect, and the multiple Fano effects coexist in our system. Moreover, the parities, defined by the odd- and even-numbered energy levels in this system, can be switched by adjusting magnetic flux phase ϕ located at the center of the quantum ring, which induces multiple controllable Fano-interference energy pathways. Therefore, the constructive and destructive multi-Fano interference transition, the Kondo and Fano resonance transition at the Fermi level, the Fano resonance and ani-resonance transition are realized in the even parity system. They can also be observed in the odd parity system when one adjusts the phase ϕ and the gate voltage Vg applied to the noninteracting QDs. The multi-quantum transitions determine some interesting transport properties such as the current switch and its multi-flatsteps, the differential conductance switch at zero bias voltage and its oscillation or quantization at the low bias voltage. These results may be useful for the observation of multiple quantum effect interplays experimentally and the design of controllable QD-based device.

  19. Synchronisation of fractional-order time delayed chaotic systems with ring connection

    NASA Astrophysics Data System (ADS)

    He, S.; Sun, K.; Wang, H.

    2016-02-01

    In this paper, synchronisation of fractional-order time delayed chaotic systems in ring networks is investigated. Based on Lyapunov stability theory, a new generic synchronisation criterion for N-coupled chaotic systems with time delay is proposed. The synchronisation scheme is applied to N-coupled fractional-order time delayed simplified Lorenz systems, and the Adomian decomposition method (ADM) is developed for solving these chaotic systems. Performance analysis of the synchronisation network is carried out. Numerical experiments demonstrate that synchronisation realises in both state variables and intermediate variables, which verifies the effectiveness of the proposed method.

  20. Vascular rings.

    PubMed

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. PMID:27301603

  1. Hepatopancreatic arterial ring: bilateral symmetric typology in human celiaco-mesenteric arterial system.

    PubMed

    Kosaka, Motohiro; Horiuchi, Kanji; Nishida, Keiichiro; Taguchi, Takehito; Murakami, Takuro; Ohtsuka, Aiji

    2002-10-01

    The celiac and mesenteric arterial system including the left gastric, splenic, common hepatic, and superior mesenteric arteries shows various types of origins, courses, ramifications and anastomoses. In order to explain the various expressions of this system, we have proposed a typological model, in which celiacomesenteric arteries develop as paired or bilaterally symmetrical primordial vessels originated from the anterior aspect of the aorta, and these vessels anastomose each other with longitudinal and horizontal pathways. Here, we report 3 unusual cases characterized by arterial rings, formed by the left gastric, left accessory hepatic, proper hepatic, anterior pancreaticoduodenal, and dorsal pancreatic arteries. The dorsal pancreatic and anterior pancreaticoduodenal arteries are located to the right and left of the embryonic pancreas developing in the dorsal mesentery, respectively. Such hepatopancreatic arterial rings simultaneously containing right and left elements can only be explained using our typological model, in which the concept of paired arteries or bilateral symmetry is introduced. PMID:12530508

  2. Performance of the RF bunch coalescing system in the Fermilab main ring

    SciTech Connect

    Martin, P.; Meisner, K.; Miller, H.; Nicholls, G.; Wildman, D.

    1985-10-01

    Both the proton and antiproton bunches which will collide in the Tevatron have longitudinal emittance greater than can be accelerated by the Main Ring from 8 GeV without large loss and emittance growth. To circumvent this restriction, several bunches of smaller intensity are accelerated in the Main Ring to an energy of 150 GeV where these bunches are coalesced into a single high-intensity bunch. Coalescing has possible uses in other applications. Applications could be any time that a beam which has been accelerated by an rf system of one frequency must be captured by another rf frequency. The bunch coalescing system is described and some preliminary coalescing results are shown.

  3. COMPUTATIONAL BEAM DYNAMICS STUDIES FOR IMPROVING THE RING INJECTION AND EXTRACTION SYSTEMS IN SNS

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Plum, Michael A; Wang, Jian-Guang

    2008-01-01

    The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated ongoing study and development by a multidisciplinary team. Results already include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertent introduction of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

  4. Position and rotation-invariant pattern recognition system by binary rings masks

    NASA Astrophysics Data System (ADS)

    Solorza, S.; Álvarez-Borrego, J.

    2015-06-01

    In this paper, algorithms invariant to position, rotation, noise and non-homogeneous illumination are presented. Here, several manners are studied to generate binary rings mask filters and the corresponding signatures associated to each image. Also, in this work it is shown that digital systems, which are based on the ?-law non-linear correlation, are ?-invariant for ?. The methodologies are tested using greyscale fossil diatoms digital images (real images), and considering the great similarity between those images the results obtained are excellent. The box plot statistical analysis and the computational cost times yield that the Bessel rings masks are the best option when the images contain a homogeneous illumination and the Fourier masks digital system is the right selection when the non-homogeneous illumination and noise is presented in the images.

  5. Thermal forces on planetary ring particles: application to the main system of Saturn

    NASA Astrophysics Data System (ADS)

    Vokrouhlický, D.; Nesvorný, D.; Dones, L.; Bottke, W. F.

    2007-08-01

    Context: The motion of small particles in planetary rings is affected in the long-term by radiation forces. While the Poynting-Robertson effect has been extensively discussed and applied to the dynamics of micron-sized ring particles, studies of thermal self-acceleration of particles are only in their infancy. Aims: We extend the pioneering work of Rubincam (2006, Icarus 184, 532) by a more thorough analytical formulation of both planetary and solar thermal forces on ring particles. Methods: Within a sparse disk model we analytically compute both seasonal and diurnal variants of the thermal forces and we demonstrate that the diurnal effect components vanish for a sample of rapidly rotating particles with randomly oriented spin axes. For sufficiently slowly rotating ring particles, though, these diurnal components might significantly modify the expected planetocentric secular drift rates of their orbits. We also take into account the orbital effects of Poynting-Robertson drag that begin to dominate the thermal forces for particles with sizes ≤5 mm. Our formulation of the Poynting-Robertson drag is the first to account properly for the influence of the planetary shadow. Results: We critically review the previous suggestion that Saturn's A and B ring boundaries might correlate with radiative null-torque orbits of small particles. Using the best estimates of optical and thermal parameters of Saturn's ring particles, we show that the millimetre to several centimetre size particles mostly drift inward to the planet with a characteristic radial speed ν_r˜ 3× 10-6 cm/s, corresponding to drift across the whole main ring system in ~ (1-5)× 108 years if the effects of inter-particle collisions are neglected. The radial speed is comparable to, or even larger than, the effective radial drift rate of small particles due to redistribution of collisional ejecta from micrometeoroid impacts. Therefore, radiation forces may be important for estimating the evolution timescales

  6. Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

    SciTech Connect

    Gao, F.; Rose, J.; Cupolo, J.; Dilgen, T.; Rose, B.; Gash, W.; Ravindranath, V.; Yeddulla, M.; Papu, J.; Davila, P.; Holub, B.; Tagger, J.; Sikora, R.; Ramirez, G.; Kulpin, J.

    2015-05-03

    The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

  7. Monitor and control systems for the SLD Cherenkov Ring Imaging Detector

    SciTech Connect

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Fernandez, F.; Hallewell, G.; Kawahara, H.; Korff, P.; Kwon, Y.; Leith, D.; Muller, D.; Nagamine, T.; Pavel, T.; Rabinowitz, L.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Toge, N.; Va'Vra, J.; Williams, S.; Whitaker, J.; Wilson, R.J.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; McHugh, S.; Mathys, L.; Morriso

    1989-10-01

    To help ensure the stable long-term operation of a Cherenkov Ring Detector at high efficiency, a comprehensive monitor and control system is being developed. This system will continuously monitor and maintain the correct operating temperatures, and will provide an on-line monitor and maintain the correct operating temperatures, and will provide an on-line monitor of the pressures, flows, mixing, and purity of the various fluids. In addition the velocities and trajectories of Cherenkov photoelectrons drifting within the imaging chambers will be measured using a pulsed uv lamp and a fiberoptic light injection system. 9 refs., 6 figs.

  8. An active feedback system to control synchrotron oscillations in the SLC Damping Rings

    SciTech Connect

    Corredoura, P.L.; Pellegrin, J.L.; Schwarz, H.D.; Sheppard, J.C.

    1989-03-01

    Initially the SLC Damping Rings accomplished Robinson instability damping by operating the RF accelerating cavities slightly detuned. In order to be able to run the cavities tuned and achieve damping for Robinson instability and synchrotron oscillations at injection an active feedback system has been developed. This paper describes the theoretical basis for the feedback system and the development of the hardware. Extensive measurements of the loop response including stored beam were performed. Overall performance of the system is also reported. 3 refs., 6 figs.

  9. Digital closed orbit feedback system for the Advanced Photon Source storage ring

    NASA Astrophysics Data System (ADS)

    Chung, Y.; Barr, D.; Decker, G.; Galayda, J.; Lenkszus, F.; Lumpkin, A.; Votaw, A. J.

    1996-09-01

    Closed orbit feedback for the Advanced Photon Source (APS) storage ring employs unified global and local feedback systems for stabilization of particle and photon beams based on digital signal processing. Hardware and software aspects of the system will be described. In particular, we will discuss global and local orbit feedback algorithms, PID (proportional, integral, and derivative) control algorithm, application of digital signal processing to compensate for vacuum chamber eddy current effects, resolution of the interaction between global and local systems through decoupling, self-correction of the local bump closure error, user interface through the APS control system, and system performance in the frequency and time domains. The system hardware, including the digital signal processor (DSPs), is distributed in 20 VME crates around the ring, and the entire feedback system runs synchronously at 4-kHz sampling frequency in order to achieve a correction bandwidth exceeding 100 Hz. The required data sharing between the global and local feedback systems is facilitated via the use of fiber-optically networked reflective memories.

  10. Improved temperature regulation of process water systems for the APS storage ring.

    SciTech Connect

    Putnam, C.; Dortwegt, R.

    2002-10-10

    Beam stability and operational reliability of critical mechanical systems are key performance issues for synchrotron accelerators such as the Advanced Photon Source (APS). Stability is influenced by temperature fluctuations of the process water (PW) used for cooling and/or temperature conditioning storage ring (SR) components such as vacuum chambers, magnets, absorbers, etc. Operational reliability is crucial in maintaining facility beam operations and remaining within downtime ''budgets.'' Water systems for the APS storage ring were originally provided with a distributive control system (DCS) capable of regulation to {+-}1.0 F, as specified by facility design requirements. After several years of operation, a particular mode of component mortality indicated a need for upgrade of the temperature control system. The upgrade that was implemented was chosen for both improved component reliability and temperature stability (now on the order of {+-}0.2 F for copper components and {+-}0.05 F for aluminum components). The design employs a network of programmable logic controllers (PLCs) for temperature control that functions under supervision of the existing DCS. The human-machine interface (HMI) of the PLC system employs RSView32 software. The PLC system also interfaces with the EPICS accelerator control system to provide monitoring of temperature control parameters. Eventual supervision of the PLC system by EPICS is possible with this design.

  11. James Webb Space Telescope Observations of Stellar Occultations by Solar System Bodies and Rings

    NASA Astrophysics Data System (ADS)

    Santos-Sanz, P.; French, R. G.; Pinilla-Alonso, N.; Stansberry, J.; Lin, Z.-Y.; Zhang, Z.-W.; Vilenius, E.; Müller, Th.; Ortiz, J. L.; Braga-Ribas, F.; Bosh, A.; Duffard, R.; Lellouch, E.; Tancredi, G.; Young, L.; Milam, Stefanie N.; the JWST “Occultations” Focus Group

    2016-01-01

    In this paper, we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of Solar System bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun-Earth Lagrange point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a byproduct of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  12. Photocatalytic Systems with Flavinium Salts: From Photolyase Models to Synthetic Tool for Cyclobutane Ring Opening.

    PubMed

    Hartman, Tomáš; Cibulka, Radek

    2016-08-01

    Two new photocatalytic systems based on flavinium species formed in situ by protonation of riboflavin-tetraacetate (1) with triflic acid or prepared in advance via alloxazine quaternization are presented as effective tools for oxidative cyclobutane ring [2 + 2] cycloreversion using visible light. The system with 1,3-dimethyl-8-trifluoromethylalloxazinium perchlorate (2c) was found to be superior allowing an acid-free mild procedure, which results in the opening of cyclobutanes with high oxidation potential (up to 2.14 V) and/or with sensitive groups (e.g., furan) without side reactions. PMID:27415962

  13. The fluid systems for the SLD Cherenkov ring imaging detector. [01

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H. . Dept. of Physics); Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw,

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C[sub 2]H[sub 6] + TMAE), radiator gas (C[sub 5]F[sub 12] + N[sub 2]) and radiator liquid (C[sub 6]F[sub 14]). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  14. The vacuum system for the PEP II high energy ring straight sections

    SciTech Connect

    Wienands, U.; Daly, E.; Kulikov, A.; Kurita, N.; Nordby, M.; Perkins, C.; Reuter, E.; Seeman, J. T.

    1995-01-01

    The six straight sections of the PEP II High Energy Ring (HER) serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. 5 refs., 7 figs.

  15. Ballistic transport in planetary ring systems due to particle erosion mechanisms. I - Theory, numerical methods, and illustrative examples

    NASA Technical Reports Server (NTRS)

    Durisen, Richard H.; Murphy, Brian W.; Cramer, Nichael Lynn; Cuzzi, Jeffrey N.; Mullikin, Thomas L.

    1989-01-01

    Ballistic transport, defined as the net radial transport of mass and angular momentum due to exchanges of meteoroid hypersonic-impact ejecta by neighboring planetary ring regions on time-scales orders-of-magnitude shorter than the age of the solar system, is presently considered as a problem in mathematical physics. The preliminary results of a numerical scheme for following the combined effects of ballistic transport and viscous diffusion demonstrate that ballistic transport generates structure near sharp edges already present in the ring-mass distribution; the entire ring system ultimately develops an undulatory structure whose length scale is typically of the order of the radial excursion of the impact ejecta.

  16. Storage Rings

    SciTech Connect

    Fischer, W.

    2011-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or

  17. Engineering vortex rings and systems for controlled studies of vortex interactions in Bose-Einstein condensates

    SciTech Connect

    Ruostekoski, Janne; Dutton, Zachary

    2005-12-15

    We study controlled methods of preparing vortex configurations in atomic Bose-Einstein condensates and their use in the studies of fundamental vortex scattering, reconnection processes, and superfluid sound emission. We explore techniques of imprinting vortex rings by means of coherently driving internal atomic transitions with electromagnetic fields which exhibit singular phase profiles. In particular, we show that a vortex ring can be prepared by two focused co-propagating Gaussian laser beams. More complex vortex systems may also be imprinted by directly superposing simpler field configurations or by programming their phase profiles on optical holograms. We analyze specific examples of two merging vortex rings in a trapped two-species {sup 87}Rb gas. We calculate the radiated sound energy in the reconnection process and show that the vortex relaxation and the redistribution of sound energy can be controlled by the imprinting process. As another creation technique, we study engineering pairs of two-dimensional point vortices in the condensates using a 'light roadblock' in ultraslow light propagation. We show how this can be used to study vortex collisions in compressible superfluids and how these collisions result in energy dissipation via phonons and, sometimes, annihilation of vortex pairs.

  18. Saturn's seasonal winds and temperature: The effect of the ring system on the troposphere and stratosphere

    SciTech Connect

    Barnet, C.D.

    1990-01-01

    The radiative properties of Saturn's rings (insolation shadowing, insolation scattering, and thermal emission) were incorporated into a seasonal, zonally-averaged, radiative-dynamical model to investigate the magnitude of small seasonal fluctuations in the troposphere and stratosphere of Saturn. Although the radiative time constant is large in Saturn's troposphere and stratosphere, the rings induce significant latitudinal insolation gradients resulting in potential disturbances in the upper stratosphere. The results of the model are compared to the Pioneer and Voyager Radio Sub-System (RSS) vertical temperature profile measurements and to the Voyager Infrared Interferometric Spectrometer (IRIS) latitudinal temperature profile measurements. In the upper stratosphere (1 to 30 mBar) the heating is dominated by methane and the model can be directly compared to the Voyager data. Below the temperature minimum the radiative time constant is sufficiently long to strongly dampen seasonal variations, however, the temperature excursions seen in the IRIS data are significantly larger than those predicted by the radiative model. The thermal effects of the strong Saturnian zonal winds are simulated with a first-order dynamical model to provide some insight into the lower boundary conditions. The remaining differences between the model and the Voyager IRIS data-sets are used to estimate the quantity of aerosol required near the tropopause region. The magnitudes of the wind and temperature perturbations, caused by the radiative effects of Saturn's rings, are discussed in the context of the future Hubble Space Telescope and the planned Cassini Saturnian Orbiter missions.

  19. The terminal Eocene event - Formation of a ring system around the earth

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.

    1980-01-01

    It is suggested that the formation of a ring system about the earth by particles and debris related to the North American strewn tektite field is responsible for the terminal Eocene event of 34 million years ago, in which severe climatic changes accompanied by widespread biological extinctions occurred. Botanical data is cited which implies a 20-C decrease in winter temperature with no change in summer temperature, and evidence of the correlation of the North American tektite fall, which is estimated to have a total mass of 10 to the 9th to 10 to the 10th tons, with the disappearance of five of the most abundant species of radiolaria is presented. The possible connection between the tektites and climatic change is argued to result from the screening of sunlight by an equatorial ring of trapped particles of extraterrestrial origin in geocentric orbit which would cut off sunlight only in the winter months. Such a ring, located at a distance of between 1.5 and 2.5 earth radii (the Roche limit) is estimated to have a lifetime of a few million years.

  20. [Case of systemic myositis and subacute sensory neuropathy concomitant with signet-ring cell carcinoma].

    PubMed

    Yasuda, Chiharu; Yakushiji, Yusuke; Tokunaga, Osamu; Hara, Hideo; Nishino, Ichizo

    2010-04-01

    A 72-year-old woman referred to our hospital because of slowly progressive (over 2 years) muscle weakness and paresthesias of the lower limbs. On neurological examination, weakness and muscle atrophies were noted in the distal upper limbs as well as the proximal lower limbs. She had also paresthesias of the legs. The level of creatinine phosphokinase (CK) was 126 IU/l. The magnetic resonance imaging demonstrated gadolinium enhancement of the nerve roots at the L4-S2 vertebrate levels. Nerve conduction study showed decreased compound muscle action potential and motor conduction velocity of tibial and peroneal nerves. Biopsy of the left biceps brachii muscle showed variations in fiber size, endomysial mononuclear cell infiltration and the findings like a rimmed vacuole. Although almost of her findings were in accord with clinical features of inclusion body myositis, strong inflammatory cellular influences allowed us to administer corticosteroid therapy. Because her weakness was well responded to steroid therapy, polymyositis was considered as differential diagnosis. Then, further examinations were investigated to search any occult neoplasm, and detected the early gastric cancer. Total gastrectomy was performed later, and the pathological diagnosis was made as a signet-ring cell carcinoma. To our knowledge, this is the first report of systemic myositis and subacute sensory neuropathy concomitant with signet-ring cell carcinoma. These symptoms might be occurred as a result of paraneoplastic syndrome associated with satellite effects of the signet-ring cell carcinoma. PMID:20411807

  1. A Performance Comparison of Tree and Ring Topologies in Distributed System

    SciTech Connect

    Min Huang

    2005-12-19

    A distributed system is a collection of computers that are connected via a communication network. Distributed systems have become commonplace due to the wide availability of low-cost, high performance computers and network devices. However, the management infrastructure often does not scale well when distributed systems get very large. Some of the considerations in building a distributed system are the choice of the network topology and the method used to construct the distributed system so as to optimize the scalability and reliability of the system, lower the cost of linking nodes together and minimize the message delay in transmission, and simplify system resource management. We have developed a new distributed management system that is able to handle the dynamic increase of system size, detect and recover the unexpected failure of system services, and manage system resources. The topologies used in the system are the tree-structured network and the ring-structured network. This thesis presents the research background, system components, design, implementation, experiment results and the conclusions of our work. The thesis is organized as follows: the research background is presented in chapter 1. Chapter 2 describes the system components, including the different node types and different connection types used in the system. In chapter 3, we describe the message types and message formats in the system. We discuss the system design and implementation in chapter 4. In chapter 5, we present the test environment and results, Finally, we conclude with a summary and describe our future work in chapter 6.

  2. Binaries and core-ring structures in self-gravitating systems.

    PubMed

    Ispolatov, I

    2005-08-01

    Low-energy states of self-gravitating systems with finite angular momentum are considered. A constraint is introduced to confine cores and other condensed objects within the system boundaries by gravity alone. This excludes previously observed astrophysically irrelevant asymmetric configurations with a single core. We show that, for an intermediate range of a short-distance cutoff and small angular momentum, the equilibrium configuration is an asymmetric binary. For larger angular momentum or for a smaller range of the short-distance cutoff, the equilibrium configuration consists of a central core and an equatorial ring. The mass of the ring varies between zero for vanishing rotation and the full system mass for the maximum angular momentum L(max) a localized gravitationally bound system can have. The value of L(max) scales as square root of ((ln(1/x0)), where x0 is a ratio of a short-distance cutoff range to the system size. An example of the soft gravitational potential is considered; the conclusions are shown to be valid for other forms of short-distance regularization. PMID:16196652

  3. Voyager 2 radio science observations of the uranian system: atmosphere, rings, and satellites.

    PubMed

    Tyler, G L; Sweetnam, D N; Anderson, J D; Campbell, J K; Eshleman, V R; Hinson, D P; Levy, G S; Lindal, G F; Marouf, E A; Simpson, R A

    1986-07-01

    Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 +/- 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale stucture throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maxim value occurs in the outer region of the in ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kdnd of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data

  4. Optical Properties of a Quantum Dot-Ring System Grown Using Droplet Epitaxy.

    PubMed

    Linares-García, Gabriel; Meza-Montes, Lilia; Stinaff, Eric; Alsolamy, S M; Ware, M E; Mazur, Y I; Wang, Z M; Lee, Jihoon; Salamo, G J

    2016-12-01

    Electronic and optical properties of InAs/GaAs nanostructures grown by the droplet epitaxy method are studied. Carrier states were determined by k · p theory including effects of strain and In gradient concentration for a model geometry. Wavefunctions are highly localized in the dots. Coulomb and exchange interactions are studied and we found the system is in the strong confinement regime. Microphotoluminescence spectra and lifetimes were calculated and compared with measurements performed on a set of quantum rings in a single sample. Some features of spectra are in good agreement. PMID:27342603

  5. Optical Properties of a Quantum Dot-Ring System Grown Using Droplet Epitaxy

    NASA Astrophysics Data System (ADS)

    Linares-García, Gabriel; Meza-Montes, Lilia; Stinaff, Eric; Alsolamy, S. M.; Ware, M. E.; Mazur, Y. I.; Wang, Z. M.; Lee, Jihoon; Salamo, G. J.

    2016-06-01

    Electronic and optical properties of InAs/GaAs nanostructures grown by the droplet epitaxy method are studied. Carrier states were determined by k · p theory including effects of strain and In gradient concentration for a model geometry. Wavefunctions are highly localized in the dots. Coulomb and exchange interactions are studied and we found the system is in the strong confinement regime. Microphotoluminescence spectra and lifetimes were calculated and compared with measurements performed on a set of quantum rings in a single sample. Some features of spectra are in good agreement.

  6. Vacuum system design for the PEP-II B Factory High-Energy Ring

    SciTech Connect

    Perkins, C.; Bostic, D.; Daly, E.

    1994-06-01

    The design of the vacuum system for the PEP-II B Factory High-Energy Ring is reviewed. The thermal design and vacuum requirements are particularly challenging in PEP-II due to high stored beam currents up to 3.0 amps in 1658 bunches. The vacuum chambers for the HER arcs are fabricated by electron beam welding extruded copper sections up to 6 m long. Design of these chambers and the vacuum PumPing configuration is described with results from vacuum and thermal analyses.

  7. POWER SUPPLY CONTROL AND MONITORING FOR THE SNS RING AND TRANSPORT SYSTEM

    SciTech Connect

    LAMBIASE,R.; OERTER,B.; PENG,S.; SMITH,J.

    2001-06-28

    There are approximately 300 magnet power supplies in the SNS accumulator ring and transport lines. Control and monitoring of the these converters will be primarily accomplished with a new Power Supply Interface and Controller (PSI/PSC) system developed for the SNS project. This PSI/PSC system provides all analog and digital commands and status readbacks in one fiber isolated module. With a maximum rate of 10KHz, the PSI/PSC must be supplemented with higher speed systems for the wide bandwidth pulsed injection supplies, and the even wider bandwidth extraction kickers. This paper describes the implementation of this PSI/PSC system, which was developed through an industry/laboratory collaboration, and the supplementary equipment used to support the wider bandwidth pulsed supplies.

  8. Introduction to the magnet and vacuum systems of an electron storage ring

    SciTech Connect

    Weng, W.T.

    1982-08-15

    An accelerator or storage ring complex is a concerted interplay of various functional systems. For the convenience of discussion we can divide it into the following systems: injector, magnet, RF, vacuum, instrumentation and control. In addition, the conventional construction of the building and radiation safety consideration are also needed and finally the beam lines, detector, data acquisition and analysis set-ups for research programs. Dr. L. Teng has given a comprehensive review of the whole complex and the operation of such a facility. I concentrate on the description of magnet and vacuum systems. Only the general function of each system and the basic design concepts will be introduced, no detailed engineering practice will be given which will be best done after a machine design is produced. For further understanding and references a table of bibliography is provided at the end of the paper.

  9. Development of a bilayer ring system for achieving high strain in commercial rheometers.

    PubMed

    Christensen, Michael B; Wolchok, Jeffrey C; Klemuk, Sarah A; Titze, Ingo R

    2015-09-18

    Mechanical stimulation of cell cultures has been shown be an effective means of enhancing ECM production. ECM produced from vocal fold fibroblast cultures has the potential for therapeutic use for vocal fold repair. However, current bioreactor designs generally fail to produce physiological relevant frequency and strain values. Here we present an approach for using commercial oscillatory rheometers and an elastic ring bilayer system to produce physiologically relevant strain values at frequencies in the range of 20-100 Hz. We demonstrate the ability to target specific strain and frequency values by manipulating system parameters, and also show that it is possible to maintain high oscillatory strains for extended periods of time. Such a system could be used to mechanically stimulate cell cultures contained within gel carrier systems and has the potential to be extended to other applications requiring high strains at low frequencies. PMID:26228712

  10. Cavity Ring-Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source

    SciTech Connect

    Nakano, Haruhisa; Tsumori, Katsuyoshi; Nagaoka, Kenichi; Shibuya, Masayuki; Kisaki, Masashi; Ikeda, Katsunori; Osakabe, Masaki; Kaneko, Osamu; Asano, Eiji; Kondo, Tomoki; Sato, Mamoru; Komada, Seiji; Sekiguchi, Haruo; Takeiri, Yasuhiko; Fantz, Ursel

    2011-09-26

    A Cavity Ring-Down (CRD) system was applied to measure the density of negative hydrogen ion (H{sup -}) in vicinity of extraction surface in the H{sup -} source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam-current with applying a similar relation of positive ion sources. In cesium seeded into ion-source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. Additionally, the measured density was proportional to the extracted beam current. These characteristics indicate the CRD system worked well for H{sup -} density measurement in the region of H{sup -} and extraction.

  11. Formation of Regular Satellites from Ancient Massive Rings in the Solar System

    NASA Astrophysics Data System (ADS)

    Crida, A.; Charnoz, S.

    2012-11-01

    When a planetary tidal disk—like Saturn’s rings—spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn’s, Uranus’, and Neptune’s satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems.

  12. The trigger system for the external target experiment in the HIRFL cooling storage ring

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhao, Lei; Liu, Jin-Xin; Lu, Yi-Ming; Liu, Shu-Bin; An, Qi

    2016-08-01

    A trigger system was designed for the external target experiment in the Cooling Storage Ring (CSR) of the Heavy Ion Research Facility in Lanzhou (HIRFL). Considering that different detectors are scattered over a large area, the trigger system is designed based on a master-slave structure and fiber-based serial data transmission technique. The trigger logic is organized in hierarchies, and flexible reconfiguration of the trigger function is achieved based on command register access or overall field-programmable gate array (FPGA) logic on-line reconfiguration controlled by remote computers. We also conducted tests to confirm the function of the trigger electronics, and the results indicate that this trigger system works well. Supported by the National Natural Science Foundation of China (11079003), the Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the CAS Center for Excellence in Particle Physics (CCEPP).

  13. The Ring of Fire - an internal illimination system for detector sensitivity and filter bandpass characterization

    SciTech Connect

    Scarpine, Victor E.; Kent, Stephen M.; Deustua, Susana E.; Sholl, Michael J.; Mufson, Stuart L.; Ott, Melanie N.; Wiesner, Matthew P.; Baptitst, Brian J.; /Indiana U.

    2010-07-01

    We describe a prototype of an illumination system, the Ring of Fire (ROF), which is used as part of an internal calibration system for large focal plane detector arrays in TMA (Three Mirror Anastigmat) telescope designs. Such designs have been proposed for the SNAP (SuperNova Acceleration Probe) version of a Joint Dark Energy Mission (JDEM). The ROF system illuminates the focal plane with a light beam the closely matches that of the telescope and is used for creating high spatial frequency flat fields and monitoring filter bandpasses for experiments that demand a highly accurate characterization of the detectors. We present measurements of a mockup of this prototype ROF design including studies in variations in illumination across a large focal plane.

  14. Generation of optical frequency combs in a fiber-ring/microresonator laser system.

    PubMed

    Guo, Changlei; Che, Kaijun; Xu, Huiying; Zhang, Pan; Tang, Deyu; Ren, Changyan; Luo, Zhengqian; Cai, Zhiping

    2016-06-01

    We propose and experimentally demonstrate a simple scheme for generating optical frequency combs (OFCs) in a fiber-ring/microresonator laser system. The ultrahigh Q whispering gallery mode microresonator is employed both as a mode reflection mirror to generate erbium lasing and as a Kerr-nonlinearity initiator that introduces optical parametric oscillation signals to form OFCs. By controlling the coupling position between the fiber taper and microresonator, optimizing the fiber polarization, as well as the pump power from a 974 nm laser diode (LD), versatile OFCs can be tuned out from single-wavelength states. The OFCs have single, multiple, or combined free spectral ranges. In addition, a Raman-gain-assisted OFC is also observed with a bandwidth of ∼230  nm. This LD-pumped and multifunctional laser system could find applications in precision spectroscopy, biochemical sensing, and optical fiber communication systems. PMID:27244418

  15. Feasibility of Injection/Extraction Systems for Muon FFAG Rings in the Neutrino Factory

    SciTech Connect

    Pasternak, J.; Berg, J.; Aslaninejad, M.; Kelliher, D.; Machida, S.

    2010-12-01

    Non-scaling FFAG rings have been proposed for muon acceleration in a neutrino factory. In order to achieve small orbit excursion and small time of flight variation, lattices with a very compact cell structure and short straight sections are required. The resulting geometry places very challenging constraints on the injection/extraction systems. The feasibility of injection/extraction is discussed and various implementations focusing on minimization of kicker/septum strength are presented. The injection and extraction systems in the nonscaling FFAG for muon acceleration in a neutrino factory were studied in the ring based on FODO lattice. The vertical direction was found to be preferential for both injection and extraction, which allows for lower kicker strengths and facilitates the distribution of kickers due to a lower phase advance per cell in comparison with the horizontal plane. It is possible to design mirror-symmetric schemes in which the kickers can be reused for both signs of muons. The disadvantage of these solutions is a need for special magnets with large aperture in the injection/extraction region due to the large kicked beam oscillations. The strengths of the required kickers are still very challenging and the fields in the septum magnets dictates the need for a superconducting design.

  16. Phenalene-phosphazene complexes: Effect of exocyclic charge densities on the cyclotriphosphazene ring system

    SciTech Connect

    Haddon, R.C.; Chichester-Hicks, S.V.; Mayo, S.L.

    1988-06-01

    The synthesis and properties of a new series of 1,9-diamino-substituted phenalene complexes of the cyclotriphosphazene ring system is described. One of the compounds is shown to be amphoteric, and this behavior allows an examination of the response of the phosphazene linkage to variations in exocyclic charge density at the spiro center in a plane perpendicular to the cyclotriphosphazene ring system. /sup 31/P NMR spectroscopy indicates that substituent lone pairs with this orientation are not effective in long-range delocalization within the phosphazene linkage (in accord with their theoretical model of spiro delocalization). An x-ray crystal structure of one compound (7) identifies the presence of clathrated molecules of chloroform together with doubly hydrogen-bonded pairs of the phenalene-phosphazene complexes in the lattice. Crystal data for 7 (C/sub 13/H/sub 8/Cl/sub 4/N/sub 5/P/sub 3/ /times/ CHCl/sub 3/): monoclinic space group P2/sub 1//c, a = 12.401 (4) /angstrom/, b = 28.404 (6) /angstrom/, c = 12.962 (3) /angstrom/, /beta/ = 91.76 (2)/degree/, V = 4564 (2) /angstrom//sup 3/, Z = 8, R = 0.050 for 4525 reflections. 24 references, 3 figures, 7 tables.

  17. A new data acquisition system for Schottky signals in atomic physics experiments at GSI's and FAIR's storage rings

    NASA Astrophysics Data System (ADS)

    Trageser, C.; Brandau, C.; Kozhuharov, C.; Litvinov, Yu A.; Müller, A.; Nolden, F.; Sanjari, S.; Stöhlker, T.

    2015-11-01

    A new continuous and broadband data acquisition system for measurements of Schottky-signals of ions revolving in a storage ring has been implemented. This set-up is capable of recording the radio frequency (RF) signal of the ions that circulate in the storage ring with a sustained acquisition rate of more than 3.5× {10}7 IQ-samples per second. This allows several harmonics of the full momentum acceptance of a storage ring to be measured at the same time. The RF signal analyzer modules are complemented by further electronic modules such as counters, precision clocks and synchronization modules that facilitate a seamless integration with main experimental data acquisitions for atomic and nuclear physics. In this contribution, the setup and first results from a test run at the experimental storage ring at GSI, Darmstadt, Germany, are presented.

  18. Vacuum system of the high energy ring of an asymmetric B-factory based on PEP

    SciTech Connect

    Barletta, W.A.; Calderon, M.O.; Wong, R. ); Jenkins, T.M. )

    1991-05-07

    The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.

  19. Reflective variable optical attenuators and fibre ring lasers for wavelength-division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Liu, He Liang

    Wavelength division multiplexing (WDM) optical fibre system is an important enabling technology to fulfill the demands for bandwidth in the modern information age. The main objective of this project is to study novel devices with the potential to enhance the performance of WDM systems. In particular, a novel reflective variable optical attenuator (RVOA) used for dynamic gain equalization (DGE) and fibre lasers based on an entirely new type of erbium-doped fibres with ultrawide tuning range were investigated theoretically and experimentally. We proposed a new type of RVOA device which could be potentially integrated with arrayed waveguide grating (AWG) to reduce the cost of DGE substantially. Initially, fibre-based RVOAs, fabricated with optical fibre components such as fibre coupler and Faraday rotator mirror, were investigated theoretically and experimentally. Larger attenuation range up to 22 dB was realized for fibre coupler-based ROVA with a Faraday rotator mirror and its polarization-dependent loss is about 0.5 dB. Then polymeric waveguide-based RVOAs were investigated theoretically and experimentally. Using an epoxy Novolak resin as core material and an UV-cured resin (Norland's NOA61) as cladding material, a polymeric waveguide RVOA was successfully fabricated. The dynamic 15 dB attenuation range was achieved and the PDL was less than 0.2 dB. The measured insertion loss of the polymeric waveguide RVOA was too large (about 18 dB) and was mainly induced by coupling loss, material loss and poor alignment. In the second part of the study, fibre ring lasers with continuous wavelength tuning over wide wavelength range and fibre ring lasers with discrete wavelength tuning were investigated. Tunable lasers are important devices in WDM systems because they could be employed as reserved sources and therefore avoiding the need to stock large inventory of lasers to cover the ITU-wavelength grid. In this project, erbium ions doped bismuth oxide glass fibres instead of

  20. The Neptune System Revisited: New Results on Moons and Rings from the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.; de Pater, I.; French, R. S.; Lissauer, J. J.

    2013-10-01

    We report on observations of Neptune's rings, arcs and inner moons as obtained by the Hubble Space Telescope during 2004-2009. These are the only Earth-based observations of the ring system obtained at visual wavelengths, permitting direct photometric comparison with the Voyager images. This allows us to determine quantitatively how the arcs have evolved from the time they were first imaged. Of the four arcs identified in 1989, the leading two have vanished, but the trailing two appear to have remained quite stable. New analysis of the images has also revealed a small moon, S/2004 N 1, orbiting between Proteus and Larissa. The body has a mean motion of 378.907 +/- 0.001 degrees per day, corresponding to semimajor axis 105,283 km. Its V magnitude is 26.5 +/- 0.3, suggesting a radius of ~ 10 km if its albedo is ~ 10%, comparable to that of the other inner moons. Tentative detections of Naiad, the smallest moon discovered by Voyager, will also be discussed.

  1. Pedology around a 6700 year old Neolithic ring ditch system in Germany

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Völkel, Jörg; Schmotz, Karl; Huerkamp, Kerstin

    2010-05-01

    The cultural landscape in Europe is the product of many different human and natural activities and processes. Settlement, clearing and farming over thousands of years are constantly transforming the landscape and the according bio- and geo-components like flora and fauna, relief, hydrology, soils and others. As Geoarchaeology tries to reconstruct certain stages of this cultural landscape development, the existence of geoarchives of the respective time period are a crucial precondition. Soil science often works with colluvium as geoarchives but that presupposes the original soil to be destroyed by erosion. Therefore there is a lack of in situ soils of certain time periods throughout Europe. During archaeological excavations conducted by the Kreisarchäologie Deggendorf in eastern Bavaria late 2008 a new Neolithic ring ditch system was discovered which dates back to 4700 BC. Beside its enormous archaeological relevance the study site offers unique possibilities for pedological studies. Situated in the loess belt of eastern Bavaria calcic luvisols form the native soils of the region. However, black soils from older floodplains, the so-called Tschernitza, are described some hundred meters beside the excavation area. In addition black sediments which fill the pits of a Neolithic settlement close to the ring ditch system have been detected. The black backfill sediments are correlated with anthropogenic settlement activities. Interestingly, the backfills of the contemporaneous ring ditch system differ. The 2 m wide and 2.5 m deep ditch functioned as an ideal trap for naturally eroded sediments. The backfills of the ditch indicate different phases of sedimentation and artificial reformation of the ditch. Furthermore, the analysis of thin sections and laboratory data (such as RFA, RDA, pedogenic oxides , magn. suszept., etc.) together with geophysical measurements point to the existence of a fully developed calcic luvisol around 6700 years ago. At the same time within some

  2. Electromagnetic Calculation of Combined Earthing System with Ring Earth Electrode and Vertical Rods for Wind Turbine

    NASA Astrophysics Data System (ADS)

    Fujii, Toshiaki; Yasuda, Yoh; Ueda, Toshiaki

    With the worldwide spread of wind turbine installations, various problems such as landscape issues, bird strikes and grid connections have arisen. Protection of wind turbines from lightning is cited as one of the main problems. Wind turbines are often struck by lightning because of their open-air locations, such as in mountainous areas, and their special configuration and very-high construction. Especially, low-voltage and control circuits can fail or suffer burnout while blades can incur serious damage if struck by lightning. Wind turbine failures caused by lightning strikes account for approximately 25% of all failures. The problem is regarded as a global one that needs immediate resolution. It is important to understand the impedance characteristics of wind turbine earthing systems from the viewpoint of lightning protection. A report from IEC TR61400-24 recommends a “ring earth electrode”. This was originally defined in IEC 61024 (currently revised and re-numbered as IEC 62305), where such an electrode is recommended to reduce touch and step voltages in households and buildings. IEC TR61400-24 also recommended additional electrodes of vertical or horizontal rods. However, these concepts have not been fully discussed from the viewpoint of its application to wind turbines. To confirm the effect of a combination of a ring earth electrode and additional vertical rods for protection of a wind turbine, this report uses the Finite Difference Time Domain (FDTD) method to present an electromagnetic transient analysis on such a wind turbine earthing system. The results show that an optimal combination can be arranged from viewpoints of lightning protection and construction cost. Thus, this report discusses how to establish a quantitative design methodology of the wind turbine earthing system to provide effective lightning protection.

  3. Small-animal whole-body imaging using a photoacoustic full ring array system

    NASA Astrophysics Data System (ADS)

    Xia, Jun; Guo, Zijian; Aguirre, Andres; Zhu, Quing; Wang, Lihong V.

    2011-03-01

    In this report, we present a novel 3D photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring transducer array, received photoacoustic signals primarily from a 2-mm-thick slice. The light was generated by a pulse laser, and can either illuminate from the top or be reshaped to illuminate the sample from the side, using a conical lens and an optical condenser. The PACT system was capable of acquiring an in-plane image in 1.6 s; by scanning the sample in the elevational direction, a 3D tomographic image could be constructed. We tested the system by imaging a cylindrical phantom made of human hairs immersed in a scattering medium. The reconstructed image achieved an in-plane resolution of 0.1 mm and an elevational resolution of 1 mm. After deconvolution in the elevational direction, the 3D image was found to match well with the phantom. The system was also used to image a baby mouse in situ; the spinal cord and ribs can be seen easily in the reconstructed image. Our results demonstrate that the PACT system has the potential to be used for fast small-animal whole-body tomographic imaging.

  4. A wireless fatigue monitoring system utilizing a bio-inspired tree ring data tracking technique.

    PubMed

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  5. A Wireless Fatigue Monitoring System Utilizing a Bio-Inspired Tree Ring Data Tracking Technique

    PubMed Central

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  6. A coplanar waveguide-fed printed antenna with complementary split ring resonator for wireless communication systems

    NASA Astrophysics Data System (ADS)

    Aznabet, Mariem; El Mrabet, Otman; Floc'h, Jean Marie; Falcone, Francisco; Drissi, M.'hamed

    2015-01-01

    In this paper, we report a new design of a compact coplanar waveguide-fed printed antenna with complementary split ring resonator (CSRR). The designed antenna consists of two CSRRs, with same geometrical parameters, printed symmetrically into the top layer. The overall volume of the proposed antenna is only 30 × 20 × 0.8 mm3 (0.58 λ0 × 0.39 λ0 × 0.015 λ0), where λ0 is the wavelength of the simulated resonance frequency. The resonance frequency of the antenna is essentially defined by geometrical parameters of the CSRR, which makes it suitable for various wireless communication systems. The characteristics of the proposed antenna have been investigated using simulation software CST Microwave Studio and experimental results. The measured and simulated results show good agreement, providing a simple and low-cost design.

  7. Saturn's rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    When seen from the unlit side, the rings of Saturn present a much different appearance from that familiar to telescopic observers. Relatively opaque areas like the B Ring turn black, while lightly populated zones, such as the C Ring and the Cassini Division, prove to excellent diffuse transmitters of sunlight. The A Ring, with intermediate opacity, is at an intermediate level of brightness.

  8. Synthesis of the ABCDEF and FGHI ring system of yessotoxin and adriatoxin

    PubMed Central

    Zhang, Yuan; Rainier, Jon D.

    2016-01-01

    Yessotoxin and adriatoxin are members of the polycyclic ether family of marine natural products. Outlined in this article is our synthetic approach to two subunits of these targets. Central to our strategy is a coupling sequence that employs an olefinic-ester cyclization reaction. As outlined, this sequence was used in two coupling sequences. First it was used to merge the A,B- and E,F-bicyclic precursors and in the process generate the C, D-rings. Second it was used to couple the F- and I-rings while building the eight-membered G-ring and subsequently the H-ring pyran. PMID:26956788

  9. Synthesis, spectroscopic investigation and computational study of 3-(1-(((methoxycarbonyl)oxy)imino)ethyl)-2H-chromen-2-one.

    PubMed

    Krishnan, K Gokula; Sivakumar, R; Thanikachalam, V; Saleem, H; Arockia doss, M

    2015-06-01

    The molecular structure and vibrational modes of 3-acetylcoumarin oxime carbonate (abbreviated as 3-ACOC) have been investigated by FT-IR, FT-Raman, NMR spectra and also by computational methods using HF and B3LYP with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths, bond angles and dihedral angles) were in good agreement with the corresponding experimental values of 3-ACOC. The calculated vibrational frequencies of normal modes from DFT method matched well with the experimental values. The complete assignments were made on the basis of the total energy distribution (TED) of the vibrational modes. NMR ((1)H and (13)C) chemical shifts were calculated by GIAO method and the results were compared with the experimental values. The other parameters like dipole moment, polarizability, first order hyperpolarizability, zero-point vibrational energy, E(HOMO), E(LUMO), heat capacity and entropy have also been computed. PMID:25748590

  10. Synthesis, spectroscopic investigation and computational study of 3-(1-(((methoxycarbonyl)oxy)imino)ethyl)-2H-chromen-2-one

    NASA Astrophysics Data System (ADS)

    Gokula Krishnan, K.; Sivakumar, R.; Thanikachalam, V.; Saleem, H.; Arockia doss, M.

    2015-06-01

    The molecular structure and vibrational modes of 3-acetylcoumarin oxime carbonate (abbreviated as 3-ACOC) have been investigated by FT-IR, FT-Raman, NMR spectra and also by computational methods using HF and B3LYP with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths, bond angles and dihedral angles) were in good agreement with the corresponding experimental values of 3-ACOC. The calculated vibrational frequencies of normal modes from DFT method matched well with the experimental values. The complete assignments were made on the basis of the total energy distribution (TED) of the vibrational modes. NMR (1H and 13C) chemical shifts were calculated by GIAO method and the results were compared with the experimental values. The other parameters like dipole moment, polarizability, first order hyperpolarizability, zero-point vibrational energy, EHOMO, ELUMO, heat capacity and entropy have also been computed.

  11. 3-(2-Amino-1,3-thia­zol-4-yl)-6-chloro-2H-chromen-2-one

    PubMed Central

    Chopra, Deepak; Choudhury, A. R.; Venugopala, K. N.; Govender, Thavendran; Kruger, Hendrik G.; Maguire, Glenn E. M.; Guru Row, T. N.

    2009-01-01

    The title compound, C12H7ClN2O2S, crystallizes with two mol­ecules in the asymmetric unit. The mol­ecular conformation is roughly planar for both these mol­ecules with maximum deviations of 0.177 (3) and 0.076 (4) Å from their respective mean planes. In the crystal, strong N—H⋯N and weak but highly directional C—H⋯O hydrogen bonds provide the links between the mol­ecules. The structure is further stabilised by aromatic π–π stacking inter­actions with centroid–centroid distances in the range 3.650 (3)–3.960 (3) Å. PMID:21578837

  12. Novel DC ring topology and protection system - a comprehensive solution for mega city power grids

    NASA Astrophysics Data System (ADS)

    Haj-Maharsi, Mohamed Yassine

    2009-07-01

    The development of mega cities leads to increased load concentration and brings additional challenges to managing the electrical grid while keeping power available for critical loads. Techniques using FACTS devices are being applied to alleviate power management difficulties and to confine faults in their originating areas in order to limit the risk of cascading failures in the grid. The addition of many FACTS devices often results in control and protection coordination difficulties, power oscillations between connected networks, subsynchronous resonance problems, and torsional interactions with nearby generator units. The most effective solution is obtained when the individual AC subsystems representing sources and loads are decoupled so a fault in a given subsystem is not propagated to another subsystem. This solution can be achieved by the deployment of a DC system where power sources and loads are connected to the DC bus through voltage source converters. For a mega city, this would be conceived as a DC ring feeding multiple loads and connected to remote and local power sources. Unfortunately, the lack of fast DC circuit breakers has been one of the key issues affecting extensive applications of DC systems with common DC buses; a DC fault would discharge all the capacitors of the DC bus and cause delays in system recovery and possibly a wide system collapse. In this research, I provide a comprehensive solution to mega city power grid problems by proposing a DC system topology that enables grid expansions without affecting existing protection settings or changing existing AC breaker ratings. I also propose the means for protecting the DC system by designing a fast DC breaker and developing a control algorithm capable of isolating DC faults without blocking converter stations or depleting DC bus capacitors. My contribution is three folds: (1) I modeled and simulated Shanghai power grid and performed a study to identify short circuit and voltage stability problems

  13. Saturn's largest ring.

    PubMed

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus. PMID:19812546

  14. Initial test results of the Los Alamos proton-storage-ring bump-magnet system

    SciTech Connect

    Rose, C.R.; Barlow, D.B.; Redd, D.B.

    1997-09-01

    An upgrade program for increasing the stored beam current in the LANSCE Proton Storage is presently under way. Part of the upgrade effort has been to design, specify, and add four bump-magnet/modulator systems to the ring. This paper describes the initial test results of the first bump-magnet/modulator system. The paper begins with an overview of the pulsed-power system including important specifications of the modulator, magnet, cabling, and control system. In the main portion of the paper, waveforms and test data are included showing the accuracy, repeatability, and stability of the magnet-current pulses. These magnet pulses are programmable both in rise and fall time as well as in amplitude. The amplitude can be set between 50 and 300 A, the rise-time is fixed at 1 ms, and the linear fall-time can be varied between 500 {mu}s and 1500 {mu}s. Other issues such as loading effects and power dissipation in the magnet-bore beamtube are examined and reported.

  15. Nonlinear effects of unbalance in the rotor-floating ring bearing system of turbochargers

    NASA Astrophysics Data System (ADS)

    Tian, L.; Wang, W. J.; Peng, Z. J.

    2013-01-01

    Turbocharger (TC) rotor-floating ring bearing (FRB) system is characterised by high speed as well as high non-linearity. Using the run-up and run-down simulation method, this paper systematically investigates the influence of unbalance on the rotordynamic characteristics of a real TC-FRB system over the speed range from 0 Hz to 3500 Hz. The rotor is discretized by the finite element method, and the desired oil film forces at each simulation step are calculated by an efficient analytical method. The imposed unbalance amount and distribution are the variables considered in the performed non-stationary simulations. The newly obtained results evidently show the distinct phenomena brought about by the variations of the unbalance offset, which confirms that the unbalance level is a critical parameter for the system response. In the meantime, the variations of unbalance distribution, i.e. out-of-phase and in-phase unbalance, can lead to entirely different simulation results as well, which proves the distribution of unbalance is not negligible during the dynamic analysis of the rotor-FRB system. Additionally, considerable effort has been placed on the description as well as discussion of a unique phenomenon termed Critical Limit Cycle Oscillation (CLC Oscillation), which is of great importance and interest to the TC research and development.

  16. Asymmetric Total Synthesis of Propindilactone G, Part 2: Enantioselective Construction of the Fully Functionalized BCDE Ring System.

    PubMed

    Zhang, Jia-Jun; You, Lin; Wang, Yue-Fan; Li, Yuan-He; Liang, Xin-Ting; Zhang, Bo; Yang, Shou-Liang; Su, Qi; Chen, Jia-Hua; Yang, Zhen

    2016-05-01

    The enantioselective synthesis of the fully functionalized BCDE tetracyclic ring system of propindilactone G (A) is reported. Several synthetic methods were developed and applied to achieve this goal, including: 1) an asymmetric Diels-Alder reaction in the presence of Hayashi's catalyst for the synthesis of optically pure key intermediate 3; 2) an intramolecular Pauson-Khand reaction (PKR) for the stereoselective synthesis of the BCDE ring with an all-carbon chiral quaternary center at the C13 position by using the TMS-substituted acetylene as the substrate; and 3) Pd-catalyzed reductive hydrogenolysis for the stereoselective synthesis of the fully functionalized BCDE tetracyclic ring system. The chemistry developed herein provided a greater understanding of the total synthesis propindilactone G (A) and its analogues. PMID:26991420

  17. MRI-compatible ultrasound heating system with ring-shaped phased arrays for breast tumor thermal therapy.

    PubMed

    Chen, Hung-Nien; Chen, Guan-Ming; Lin, Bo-Sian; Lien, Pi-Hsien; Chen, Yung-Yaw; Chen, Gin-Shin; Lin, Win-Li

    2013-01-01

    Therapeutic ultrasound transducers can carry out precise and efficient power deposition for tumor thermal therapy under the guidance of magnetic resonance imaging. For a better heating, organ-specific ultrasound transducers with precision location control system should be developed for tumors located at various organs. It is feasible to perform a better heating for breast tumor thermal therapy with a ring-shaped ultrasound phased-array transducer. In this study, we developed ring-shaped phased-array ultrasound transducers with 1.0 and 2.5 MHz and a precision location control system to drive the transducers to the desired location to sonicate the designated region. Both thermo-sensitive hydrogel phantom and ex vivo fresh pork were used to evaluate the heating performance of the transducers. The results showed that the ring-shaped phased array ultrasound transducers were very promising for breast tumor heating with the variation of heating patterns and without overheating the ribs. PMID:24110540

  18. Environmental Assessment of EL Paso's Upper and Lower Valley Canal Systems Using Tree Ring Analysis

    NASA Astrophysics Data System (ADS)

    Garcia, S.; Espinosa, S.

    2012-12-01

    Dendrochronology, or tree-ring dating, is the science of dating of past environmental events or climatic changes utilizing tree ring growth patterns. The width of the rings of certain species of trees (i.e. Populus fremontii) are dependent on regional precipitation levels or the abundance of local water sources. Therefore thick rings are produced during wet years and, inversely, narrow rings during dry years. This growth can also be affected by, and date, such factors as slope gradient, soil properties, temperature and snow accumulation. The more a tree's rate of growth has been limited by such environmental factors, the more variation in ring to ring growth will be present and the higher probability of dating such factors. Trees showing a lack of ring width variability rings have generally constant environmental or climatic conditions and indicate that no environmental or climatic changes have occurred. Our study will examine the tree ring of the Rio Grande Cottonwood (Populus fremontii), due to its short life span, rapid growth, and wide spread occurrence in our proposed study area. Our study area will encompass sites along the Rio Grande, canals and residential areas in El Paso County. Our first goal will be to investigate the possibility of identifying environmental contaminants stored within various xylem tissue members of the tree rings and ascertaining dates and regional concentrations of heavy metals and therefore identifying possible sources of contamination. The second goal will be to use dendrochronology to identify and date any growth stress or impedance due to the effects of over pumping, canal lining, and flood control methods in the study area.

  19. Intravaginal rings as delivery systems for microbicides and multipurpose prevention technologies

    PubMed Central

    Thurman, Andrea Ries; Clark, Meredith R; Hurlburt, Jennifer A; Doncel, Gustavo F

    2013-01-01

    There is a renewed interest in delivering pharmaceutical products via intravaginal rings (IVRs). IVRs are flexible torus-shaped drug delivery systems that can be easily inserted and removed by the woman and that provide both sustained and controlled drug release, lasting for several weeks to several months. In terms of women’s health care products, it has been established that IVRs effectively deliver contraceptive steroids and steroids for the treatment of postmenopausal vaginal atrophy. A novel application for IVRs is the delivery of antiretroviral drugs for the prevention of human immunodeficiency virus (HIV) genital infection. Microbicides are antiviral drugs delivered topically for HIV prevention. Recent reviews of microbicide IVRs have focused on technologies in development and optimizing ring design. IVRs have several advantages, including the ability to deliver sustained drug doses for long periods of time while bypassing first pass metabolism in the gut. IVRs are discreet, woman-controlled, and do not require a trained provider for placement or fitting. Previous data support that women and their male sexual partners find IVRs highly acceptable. Multipurpose prevention technology (MPT) products provide protection against unintended/mistimed pregnancy and reproductive tract infections, including HIV. Several MPT IVRs are currently in development. Early clinical testing of new microbicide and MPT IVRs will require a focus on safety, pharmacokinetics and pharmacodynamics. Specifically, IVRs will have to deliver tissue concentrations of drugs that are pharmacodynamically active, do not cause mucosal alterations or inflammation, and do not change the resident microbiota. The emergence of resistance to antiretrovirals will need to be investigated. IVRs should not disrupt intercourse or have high rates of expulsion. Herein, we reviewed the microbicide and MPT IVRs currently in development, with a focus on the clinical aspects of IVR assessment and the challenges

  20. Flight test results of the strapdown ring laser gyro tetrad inertial navigation system

    NASA Technical Reports Server (NTRS)

    Carestia, R. A.; Hruby, R. J.; Bjorkman, W. S.

    1983-01-01

    A helicopter flight test program undertaken to evaluate the performance of Tetrad (a strap down, laser gyro, inertial navigation system) is described. The results of 34 flights show a mean final navigational velocity error of 5.06 knots, with a standard deviation of 3.84 knots; a corresponding mean final position error of 2.66 n. mi., with a standard deviation of 1.48 n. mi.; and a modeled mean position error growth rate for the 34 tests of 1.96 knots, with a standard deviation of 1.09 knots. No laser gyro or accelerometer failures were detected during the flight tests. Off line parity residual studies used simulated failures with the prerecorded flight test and laboratory test data. The airborne Tetrad system's failure--detection logic, exercised during the tests, successfully demonstrated the detection of simulated ""hard'' failures and the system's ability to continue successfully to navigate by removing the simulated faulted sensor from the computations. Tetrad's four ring laser gyros provided reliable and accurate angular rate sensing during the 4 yr of the test program, and no sensor failures were detected during the evaluation of free inertial navigation performance.

  1. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  2. A new classification system for bacterial Rieske non-heme iron aromatic ring-hydroxylating oxygenases

    PubMed Central

    Kweon, Ohgew; Kim, Seong-Jae; Baek, Songjoon; Chae, Jong-Chan; Adjei, Michael D; Baek, Dong-Heon; Kim, Young-Chang; Cerniglia, Carl E

    2008-01-01

    Background Rieske non-heme iron aromatic ring-hydroxylating oxygenases (RHOs) are multi-component enzyme systems that are remarkably diverse in bacteria isolated from diverse habitats. Since the first classification in 1990, there has been a need to devise a new classification scheme for these enzymes because many RHOs have been discovered, which do not belong to any group in the previous classification. Here, we present a scheme for classification of RHOs reflecting new sequence information and interactions between RHO enzyme components. Result We have analyzed a total of 130 RHO enzymes in which 25 well-characterized RHO enzymes were used as standards to test our hypothesis for the proposed classification system. From the sequence analysis of electron transport chain (ETC) components of the standard RHOs, we extracted classification keys that reflect not only the phylogenetic affiliation within each component but also relationship among components. Oxygenase components of standard RHOs were phylogenetically classified into 10 groups with the classification keys derived from ETC components. This phylogenetic classification scheme was converted to a new systematic classification consisting of 5 distinct types. The new classification system was statistically examined to justify its stability. Type I represents two-component RHO systems that consist of an oxygenase and an FNRC-type reductase. Type II contains other two-component RHO systems that consist of an oxygenase and an FNRN-type reductase. Type III represents a group of three-component RHO systems that consist of an oxygenase, a [2Fe-2S]-type ferredoxin and an FNRN-type reductase. Type IV represents another three-component systems that consist of oxygenase, [2Fe-2S]-type ferredoxin and GR-type reductase. Type V represents another different three-component systems that consist of an oxygenase, a [3Fe-4S]-type ferredoxin and a GR-type reductase. Conclusion The new classification system provides the following

  3. Biocompatibility and Systemic Safety of a Novel Implantable Annuloplasty Ring for the Treatment of Mitral Regurgitation in a Minipig Model.

    PubMed

    Ramot, Yuval; Rousselle, Serge D; Yellin, Nadav; Willenz, Udi; Sabag, Itai; Avner, Avi; Nyska, Abraham

    2016-07-01

    Prosthetic annuloplasty rings are a common treatment modality for mitral regurgitation, and recently, percutaneous implantation techniques have gained popularity due to their favorable safety profile. Although in common use, biocompatibility of annuloplasty rings has been reported only sparsely in the literature, and none of these reports used the percutaneous technique of implantation. We report on the biocompatibility and the systemic safety of a novel transcatheter mitral valve annuloplasty ring (AMEND™) in 6 minipigs. This device is composed of a nitinol tube surrounded by a braided polyethylene terephthalate fabric tube. The device produced no adverse inflammatory response, showing gradual integration between the metal ring and the fabric by normal host fibrocellular response, leading to complete neoendocardium coverage. There was no evidence for adverse reactions, rejection, or intolerance in the valvular structure. In 2 animals, hemopericardium resulted from the implantation procedure, leading to right-sided cardiac insufficiency with pulmonary edema and liver congestion. The findings reported herein can serve as a case study for the expected healing pathology reactions after implantation of transcatheter mitral valve annuloplasty rings. PMID:26922814

  4. Limits on Pluto's ring system from the June 12 2006 stellar occultation and implications for the New Horizons impact hazard

    NASA Astrophysics Data System (ADS)

    Throop, Henry B.; French, Richard G.; Shoemaker, Kevin; Olkin, Cathy B.; Ruhland, Trina R.; Young, Leslie A.

    2015-01-01

    The Pluto system passed in front of a 15th magnitude star on 12 June 2006. We observed this occultation from the 3.9 m Anglo-Australian Telescope (AAT), and took photometric observations every 100 ms for 3 h. Our three-hour baseline of data provides among the longest and highest-quality occultation dataset of the Pluto system ever taken. Results on Pluto's atmospheric structure from these data have been previously reported (Young, E.F. [2008]. Astron. J. 136, 1757-1769). Here we report on limits for rings, ring arcs, and small satellites within the system. We find a 3 σ upper limit on the normal optical depth of τ < 0.07 for narrow rings of width 2.4 km, and τ < 5 ×10-3 for rings of width 1500 km. We also detect no discrete objects of radius 220 m or larger along the occultation path. Motivated by the upcoming flyby of New Horizons through the Pluto system, we estimate the dust impact hazard to the spacecraft based on our optical depth limits and those derived from imaging with the Hubble Space Telescope.

  5. Jupiter's Main Ring/Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (28.5 miles) per picture element (pixel) along Jupiter's rings. Because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow, peering back toward the Sun; the ring was approximately 2.3 million kilometers (1.4 million miles) away. The arc on the far right of the image is produced when sunlight is scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts - - a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, outside the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the figure's far left side. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow. Some radial structure is barely visible across the ring's ansa (top image). A faint mist of particles can be seen above and below the main rings. This vertically extended 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces pushing the smallest grains out of the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. To accentuate faint features in the bottom image of the ring halo, different brightnesses are shown through color. Brightest features are white or yellow and the

  6. Circumbinary ring, circumstellar disks, and accretion in the binary system UY Aurigae

    SciTech Connect

    Tang, Ya-Wen; Ho, Paul T. P.; Dutrey, Anne; Guilloteau, Stéphane; Di Folco, Emmanuel; Piétu, Vincent; Gueth, Fréderic; Beck, Tracy; Boehler, Yann; Bary, Jeff; Simon, Michal

    2014-09-20

    Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary (CB) disks may be in the midst of planet formation. However, there are very few CB disks detected. We revisit one of the known CB disks, the UY Aurigae system, and probe {sup 13}CO 2-1, C{sup 18}O 2-1, SO 5(6)-4(5) and {sup 12}CO 3-2 line emission and the thermal dust continuum. Our new results confirm the existence of the CB disk. In addition, the circumstellar (CS) disks are clearly resolved in dust continuum at 1.4 mm. The spectral indices between the wavelengths of 0.85 mm and 6 cm are found to be surprisingly low, being 1.6 for both CS disks. The deprojected separation of the binary is 1.''26 based on our 1.4 mm continuum data. This is 0.''07 (10 AU) larger than in earlier studies. Combining the fact of the variation of UY Aur B in R band, we propose that the CS disk of an undetected companion UY Aur Bb obscures UY Aur Ba. A very complex kinematical pattern inside the CB disk is observed due to a mixing of Keplerian rotation of the CB disk, the infall and outflow gas. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.

  7. A new virtual ring-based system matrix generator for iterative image reconstruction in high resolution small volume PET systems.

    PubMed

    Li, K; Safavi-Naeini, M; Franklin, D R; Han, Z; Rosenfeld, A B; Hutton, B; Lerch, M L F

    2015-09-01

    A common approach to improving the spatial resolution of small animal PET scanners is to reduce the size of scintillation crystals and/or employ high resolution pixellated semiconductor detectors. The large number of detector elements results in the system matrix--an essential part of statistical iterative reconstruction algorithms--becoming impractically large. In this paper, we propose a methodology for system matrix modelling which utilises a virtual single-layer detector ring to greatly reduce the size of the system matrix without sacrificing precision. Two methods for populating the system matrix are compared; the first utilises a geometrically-derived system matrix based on Siddon's ray tracer method with the addition of an accurate detector response function, while the second uses Monte Carlo simulation to populate the system matrix. The effectiveness of both variations of the proposed technique is demonstrated via simulations of PETiPIX, an ultra high spatial resolution small animal PET scanner featuring high-resolution DoI capabilities, which has previously been simulated and characterised using classical image reconstruction methods. Compression factors of 5 x 10(7) and 2.5 x 10(7)are achieved using this methodology for the system matrices produced using the geometric and Monte Carlo-based approaches, respectively, requiring a total of 0.5-1.2 GB of memory-resident storage. Images reconstructed from Monte Carlo simulations of various point source and phantom models, produced using system matrices generated via both geometric and simulation methods, are used to evaluate the quality of the resulting system matrix in terms of achievable spatial resolution and the CRC, CoV and CW-SSIM index image quality metrics. The Monte Carlo-based system matrix is shown to provide the best image quality at the cost of substantial one-off computational effort and a lower (but still practical) compression factor. Finally, a straightforward extension of the virtual ring

  8. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  9. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  10. Features in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Esposito, Larry W.; Harris, Craig C.; Simmons, Karen E.

    1987-01-01

    A systematic, uniform search of Voyage 2 photopolarimeter system (PSS) data set for all significant features of Saturn's rings is described. On August 25, 1981, the PSS observed the occultation of the star Delta Scorpii by the rings of Saturn, and the timing of the data taking was rapid enough that the spatial resolution in the radial direction in the ring plane was better than 100 m. Tabular information and figures for 216 significant features that were found are presented.

  11. Synthesis of models of the BC ring systems of MPC1001 and MPC1001F.

    PubMed

    Dong, Shuai; Indukuri, Kiran; Clive, Derrick L J; Gao, Jin-Ming

    2016-07-01

    Piperazinedione 13, representing the BC rings of the anti-prostate cancer fungal metabolite MPC1001, was prepared by a route in which a sulfur-stabilized carbanion derived from 22 cyclizes onto the terminal ester of the pendant chain attached to N(1). Another model, 14, was synthesized by cyclization of an α-ketoamide nitrogen onto an ester; 14 represents the BC rings of MPC1001F. PMID:27284641

  12. Synthesis of the A-D Ring System of the Gambieric Acids.

    PubMed

    Clark, J Stephen; Romiti, Filippo; Sieng, Bora; Paterson, Laura C; Stewart, Alister; Chaudhury, Subhabrata; Thomas, Lynne H

    2015-10-01

    The A-D fragment of gambieric acids A and C has been synthesized using an asymmetric Tsuji-Trost allylation reaction to couple the two key segments. The A ring fragment has been prepared by a short and highly efficient route involving diastereoselective Lewis acid mediated alkylation of an acetal. Iterative ring-closing metathesis reactions have been used to construct cyclic ethers and assemble the tricyclic B-D fragment. PMID:26367818

  13. Understanding the Dynamical Evolution of the Earth Radiation Belt and Ring Current Coupled System

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Usanova, Maria; Kellerman, Adam; Drozdov, Alexander

    2016-07-01

    Modeling and understanding the ring current and radiation belt-coupled system has been a grand challenge since the beginning of the space age. In this study we show long-term simulations with a 3D Versatile Electron Radiation Belt (VERB) code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. Simulations can reproduce long term variations of the electron radiation belt fluxes and show the importance of local acceleration, radial diffusion, loss to the atmosphere and loss to the magnetopause. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. VERB simulations show that the lower energy inward transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show that at energies of 100s of keV, a number of processes work simultaneously, including convective transport, radial diffusion, local acceleration, loss to the loss cone and loss to the magnetopause. The results of the simulation of the March 2013 storm are compared with Van Allen Probes observations.

  14. An AB initio study of intramolecular hydrogen-bonding interactions in four-, five- and six-membered ring systems

    NASA Astrophysics Data System (ADS)

    George, Philip; Bock, Charles W.; Trachtman, Mendel

    Using the 4-31G basis set augmented with polarization functions on the S-atom all geometrical parameters have been optimized for the planar chain and ring conformers (related by 180° rotation of the OH, SH or NH group) of acrylic acid, the three monothioperformic acids,α-hydroxyacrolein, formyl and thioformylhydroxylamine, glyoxalmonoimine, formimidol and glyoxalmonooxime. The changes in bond lengths and bond angles which accompany the conversion of the chain into the ring conformer are classified under ten headings for a total of eight four-membered, nine five-membered and three six-membered ring systems. Systematic trends are found, indicative of electron transfer, which support the hypothesis that there is a hydrogen-bonding type of interaction in the four-as well as in the five- and six-membered rings. The change in total molecular energy for the conversion reaction is divided up into distortion and bonding energy components, and each partitioned in terms of the expectation energy differencnes ΔEK, ΔVee, ΔVnn and ΔVen. The nature of the distortion and bonding steps, whether attractive-dominant or repulsive-dominant, is correlated with ring size and the presence (or absence) of heavy atoms external to the ring. The internuclear disease OH, O…O and H … O in the OH … O(=C) hydrogen bridge are compared with experimental values for intermolecular hydrogen bonds, and the present findings are discussed in relation to studies in the literature on electron density distributions and chages in Mulliken gross electronic populations.

  15. Parameterization of a multiagent system for roof edge detection: an application to growth ring detection on fish otoliths

    NASA Astrophysics Data System (ADS)

    Guillaud, Anne; Benzinou, Abdessalam; Troadec, Herve; Rodin, Vincent; Le Bihan, Jean

    2000-03-01

    In this paper we present a method of segmentation using a multiagent system, and an application to fish otolith growth ring detection. The otoliths images are composed of alternative concentric dark and light rings, the number of which increases with the age of the fish. Up to now, the identification of growth rings, for age estimation, is routinely achieved by human readers, but this task is tedious and depends on the reader's subjectivity. The system proposed here is composed of several agents whose individual task is to detect local extremes on a grayscale image. For this aim the agents are provided with sensors on the gray levels of the image. By computing the mean gray level of two sensors placed in front of it, the agent, if it searches for light rings (respectively dark) will decide to turn in the direction of the lighter (respectively darker) sensor. The path of the agents has been tested as a roof edge detector, using the Canny criteria: good detection, good localization, and low multiple response, in order to choose the best parameters ruling the agents behavior, according to the image structures. Tests have been first achieved on synthetic images, and then on otoliths images.

  16. On the role of a coumarin derivative for sensing applications: Nucleotide identification using a micellar system.

    PubMed

    Bettoschi, Alexandre; Ceglie, Andrea; Lopez, Francesco; Meli, Valeria; Murgia, Sergio; Tamburro, Manuela; Caltagirone, Claudia; Cuomo, Francesca

    2016-09-01

    The recognition of nucleotides is of crucial importance because they are the basic constituents of nucleic acids. The present study is focused on the selective interaction between a novel amphiphilic fluorophore containing coumarin and imidazole, CI (1-methyl-3-(12-((2-oxo-2H-chromen-7-yl)oxy)dodecyl)-1H-imidazol-3-ium bromide), and different nucleotide-monophosphates (NMPs). It was supposed that the solubilization of the low water soluble CI in a micelle system of hexadecyltrimethylammonium chloride (CTAC) would make the coumarin moiety of CI available to the interaction with the water-soluble NMPs. Changes in CTAC critical micelle concentration suggested that CI strongly interacted with the host cationic surfactant, thus forming a positively charged interface enriched with coumarin able to interact with the anionic NMPs. Steady-state fluorescence quenching revealed that CI/CTAC system was capable of distinguish between purine- and pyrimidine-based nucleotides. A modified Stern-Volmer equation permitted the use of a quenching model that accounted for the possible interactions between the micelles and the nucleotides. The data analysis allowed calculating selective parameters that differentiated according to the type of nucleotide either at 25 or 50°C. Our results established the utility of the novel coumarin derivative fluorophore, supported by the simple and suitable micellar systems, as a tool for DNA sensing applications. PMID:27236839

  17. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system

    PubMed Central

    Mauk, B H

    2014-01-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes. PMID:26167438

  18. Voyager 2 and the Uranian rings

    SciTech Connect

    Porco, C.C.

    1986-12-01

    Voyager 2 data on the Uranian disk system are presented and examined. The disk system consists of nine narrow rings, ranging in width from a few km to about 100 km. The Uranian rings are eccentric, inclined to the planet's equatorial plane, and precessing. The Uranian ring characteristics detected in the Voyager data are described and compared with those of the Saturn rings. The origin and maintenance of the rings are discussed, and the particle distribution in the ring system is studied.

  19. Jupiter's Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (km) per picture element (pixel) along the rings; however, because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow peering back toward the Sun; the ring was approximately 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts -- a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, which lies exterior to the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the far left side of the figure. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow.

    A faint mist of particles can be seen above and below the main rings; this vertically extended, toroidal 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces which can push small grains out of the ring plane. Halo material is present across this entire image, implying that it reaches more than 27,000 km above the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. In order to accentuate faint features in the image, different brightnesses are shown through color, with the brightest

  20. The Gravity Field of the Uranian System and the Orbits of the Uranian Satellites and Rings

    NASA Astrophysics Data System (ADS)

    Jacobson, Robert A.

    2007-10-01

    Jacobson et al. (1992 AJ 103, 2068) determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager spacecraft. French et al. (1988 Icarus 73, 349) determined the orbits of the Uranian rings, the orientation of the Uranian pole, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. In this paper we redetermine the gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Moreover, we process the observations and determine the orbits and pole in the International Celestial Reference Frame (ICRF) rather than the FK4/B1950 frame used previously. We also utilitize the Voyager trajectory recently reconstructed in the ICRF (Jacobson and Rush, AAS Paper 07-319, 2007 AAS/AIAA Astrodynamics Specialist Conference).

  1. Dust Production By Hypothetical Satellites In The Secondary Ring-moon System Of Uranus

    NASA Astrophysics Data System (ADS)

    Sfair, Rafael; Giuliatti Winter, S. M.

    2010-10-01

    The population of the ν and μ rings of Uranus is mostly composed by micrometric particles (de Pater et al, 2006), which can be strongly disturbed by the solar radiation pressure (SRP). Sfair & Giuliatti Winter (2009) showed that the combination of the SRP with the planetary oblateness and the gravitational perturbation of the closest satellites results in a series of close encounters and sometimes collisions with the small nearby satellites. When a collision occurs the probably result is the deposition of particles onto the surface of these satellites. Since this mechanism tends to cause a depletion of material of the rings, we investigate additional sources for these dust particles. Following the method presented in Krivov et al. (2002) and adopting a rough estimative of the flux of interplanetary meteoroids at Uranus' orbit, we calculated the amount of ejecta produced by hypervelocity impacts. If we assume that these collisions are effective in order to create more debris than the mass of the impactor, due to the small cross section of the satellites, the production rate is only about few grams per second. We also investigated if a supplementary amount of material can be generated by collisions of interplanetary projectiles with a population of meter-to-kilometer bodies embedded within the rings, since these bodies may provide an addition of effective cross section area to the impactors. As a preliminary analysis we analyzed a sample of hypothetical satellites located at the peak of the brightness profile of each ring. We restricted ourselves to satellites smaller than the observational threshold of 5 km. Although a sample of moonlets smaller than 5 km can survive at the ν ring without cause any perturbation in the eccentricity larger than 1E-3 of the nearby satellites, those moonlets at the μ ring disturb the orbit of Mab.

  2. Redesign of solid rocket booster/external tank attachment ring for the space transportation system

    NASA Technical Reports Server (NTRS)

    Mccomb, Harvey G., Jr. (Compiler)

    1987-01-01

    An improved design concept is presented for the Space Shuttle solid rocket booster (SRB)/external tank (ET) attachment ring structural component. This component picks up three struts which attach the aft end of each SRB to the ET. The concept is a partial ring with carefully tapered ends to distribute fastener loads safely into the SRB. Extensive design studies and analyses were performed to arrive at the concept. Experiments on structural elements were performed to determine material strength and stiffness characteristics. Materials and fabrication studies were conducted to determine acceptable tolerances for the design concept. An overview is provided of the work along with conclusions and major recommendations.

  3. A Route to the C,D,E Ring System of the Aspidosperma Alkaloids.

    PubMed

    Giampa, Geoffrey M; Fang, Jian; Brewer, Matthias

    2016-08-19

    A short synthetic sequence leading to the formation of the C,D,E-ring subunit of the Aspidosperma alkaloids is reported. This route is based on a ring fragmentation/intramolecular azomethine ylide 1,3-dipolar cycloaddition reaction sequence that gives the desired tricyclic product as a single diastereomer. A γ-amino-β-hydroxy-α-diazo carbonyl compound is shown to fragment in the presence of a Lewis acid to give an iminium product that can be directly reduced to the corresponding amine. PMID:27500799

  4. Radiochemical separations by the ring-oven technique-IV The system (144)Ce/(144)Pr.

    PubMed

    Klockow, D; Böhmer, R G

    1969-08-01

    By using filter papers impregnated with a manganese oxide hydrate having an average oxidation number of + 3, it is possible to separate (144)Pr from (144)Ce rapidly by the ring-oven technique. With 0.06-0.07M trichloracetic acid as wash-solution, the daughter nuclide can be concentrated in the ring zone with 80-90% yield and decontamination factors > 10(3). The half-life of the separated (144)Pr was found to be 17.60 +/- 0.05 min. The behaviour of other fission nuclides under the same conditions was also investigated. PMID:18960624

  5. Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2004-01-01

    The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

  6. Merging tree ring chronologies and climate system model simulated temperature by optimal interpolation algorithm in North America

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Xing, Pei; Luo, Yong; Zhao, Zongci; Nie, Suping; Huang, Jianbin; Wang, Shaowu; Tian, Qinhua

    2015-04-01

    A new dataset of annual mean surface temperature has been constructed over North America in recent 500 years by performing optimal interpolation (OI) algorithm. Totally, 149 series totally were screened out including 69 tree ring width (MXD) and 80 tree ring width (TRW) chronologies are screened from International Tree Ring Data Bank (ITRDB). The simulated annual mean surface temperature derives from the past1000 experiment results of Community Climate System Model version 4 (CCSM4). Different from existing research that applying data assimilation approach to (General Circulation Models) GCMs simulation, the errors of both the climate model simulation and tree ring reconstruction were considered, with a view to combining the two parts in an optimal way. Variance matching (VM) was employed to calibrate tree ring chronologies on CRUTEM4v, and corresponding errors were estimated through leave-one-out process. Background error covariance matrix was estimated from samples of simulation results in a running 30-year window in a statistical way. Actually, the background error covariance matrix was calculated locally within the scanning range (2000km in this research). Thus, the merging process continued with a time-varying local gain matrix. The merging method (MM) was tested by two kinds of experiments, and the results indicated standard deviation of errors can be reduced by about 0.3 degree centigrade lower than tree ring reconstructions and 0.5 degree centigrade lower than model simulation. During the recent Obvious decadal variability can be identified in MM results including the evident cooling (0.10 degree per decade) in 1940-60s, wherein the model simulation exhibit a weak increasing trend (0.05 degree per decade) instead. MM results revealed a compromised spatial pattern of the linear trend of surface temperature during a typical period (1601-1800 AD) in Little Ice Age, which basically accorded with the phase transitions of the Pacific decadal oscillation (PDO) and

  7. Using a double-frequency RF system to facilitate on-axis beam accumulation in a storage ring

    NASA Astrophysics Data System (ADS)

    Jiang, B. C.; Zhao, Z. T.; Tian, S. Q.; Zhang, M. Z.; Zhang, Q. L.

    2016-04-01

    An on-axis injection scheme using a double-frequency RF system in a storage ring with small dynamic aperture is proposed. By altering RF voltages, empty RF buckets can be created which will be used for on-axis injection. After bunches are injected, a reverse RF voltage altering process is performed and the injected bunches can be longitudinally dumped to the main RF buckets. The scheme allows reaping the advantages of the on-axis injection while still performing accumulation.

  8. The gravito-electrodynamics of charged dust in planetary ring systems

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.; Hill, J. R.; Northrop, T. G.

    1982-01-01

    The dynamics of micron and submicron sized dust grains moving under the combined influence of planetary gravitation and the electromagnetic forces within the corotating regions of planetary magnetospheres are discussed. Magnetogravitational capture of charged grains in planetary rings is outlined. The adiabatic motion of charged dust is reviewed.

  9. Ballistic transport in planetary ring systems due to particle erosion mechanisms. II - Theoretical models for Saturn's A- and B-ring inner edges

    NASA Technical Reports Server (NTRS)

    Durisen, Richard H.; Bode, Paul W.; Cuzzi, Jeffrey N.; Cederbloom, Steven E.; Murphy, Brian W.

    1992-01-01

    The present numerical simulations and analytic arguments show that many of the common morphological features of the Saturn A- and B-ring inner-edge regions are due to 'ballistic transport', or the net radial transport of mass and angular momentum generated by exchanges of meteoroid impact ejecta. It is suggested that the observed 100-km undulatory structure of the inner B-ring arises from ballistic transport echoing of the inner edge. A strongly prograde ejecta-distribution function is used to fit the edge-region features.

  10. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    NASA Astrophysics Data System (ADS)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  11. Implementation status of the global and local beam position feedback systems for the Advanced Photon Source storage ring

    SciTech Connect

    Chung, Y.; Barr, D.; Decker, G.; Galayda, J.; Kirchman, J.; Lenkszus, F.; Lumpkin, A.; Votaw, A.J.

    1995-07-01

    The Advanced Photon Source (APS) is implementing an extensive beam position feedback system for both global and local stabilization of particle and photon beams based on digital signal processing. The description and operational experience of the system will be given in this paper. In particular, we will discuss the underlying fundamental principles, hardware layout, controls interface, and automatic software generation for multiple digital signal processors (DSPS) distributed in 20 VME crates around the ring. The feedback system runs at 4-kHz sampling frequency in order to achieve the correction bandwidth of approximately 100 Hz. For the maximum correction efficiency and resolution of conflicts among multiple local feedback systems due to the local bump closure error, the global and local feedback systems are combined into a single unified system. This novel approach is made possible through data sharing among the global and local systems via the fiber-optically networked reflective memories.

  12. Non-contacting fluid ring seal systems for railcar axle bearing systems: Quarterly progress report No. 1, June 15 to September 15, 1987

    SciTech Connect

    Not Available

    1987-01-01

    The main objectives of this DOE contract is the technical development of a practical, cost effective Fluid Ring seal system capable of: Drastically reducing locomotive drawbar traction power requirements by lowering seal friction losses prevalent in present railcar axle bearing systems; increasing reliability and safety of railroad cars by minimizing bearing lubricant leakage and minimizing bearing ''hot boxes''; and improving the productivity of the railway transportation systems by reducing rolling stock ''outages'' due to long seal life. 14 refs.

  13. Efficient Biosynthesis of Fungal Polyketides Containing the Dioxabicyclo-octane Ring System.

    PubMed

    Mao, Xu-Ming; Zhan, Zha-Jun; Grayson, Matthew N; Tang, Man-Cheng; Xu, Wei; Li, Yong-Quan; Yin, Wen-Bing; Lin, Hsiao-Ching; Chooi, Yit-Heng; Houk, K N; Tang, Yi

    2015-09-23

    Aurovertins are fungal polyketides that exhibit potent inhibition of adenosine triphosphate synthase. Aurovertins contain a 2,6-dioxabicyclo[3.2.1]octane ring that is proposed to be derived from a polyene precursor through regioselective oxidations and epoxide openings. In this study, we identified only four enzymes required to produce aurovertin E. The core polyketide synthase produces a polyene α-pyrone. Following pyrone O-methylation by a methyltransferase, a flavin-dependent mono-oxygenase and an epoxide hydrolase can iteratively transform the terminal triene portion of the precursor into the dioxabicyclo[3.2.1]octane scaffold. We demonstrate that a tetrahydrofuranyl polyene is the first stable intermediate in the transformation, which can undergo epoxidation and anti-Baldwin 6-endo-tet ring opening to yield the cyclic ether product. Our results further demonstrate the highly concise and efficient ways in which fungal biosynthetic pathways can generate complex natural product scaffolds. PMID:26340065

  14. Earth: A Ringed Planet?

    NASA Astrophysics Data System (ADS)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  15. Analysis and design modifications for upgrade of storage ring bump pulse system driving the injection bump magnets at the ALS

    SciTech Connect

    Stover, G.D.

    1995-04-01

    A fast (4.0 ms half period) resonant discharge pulse system, using SCRs, was designed and constructed to drive the injection bump magnet system at the Advanced Light Source (ALS). The commissioning process revealed a high frequency resonance (T = 800 NS) superimposed on the driver discharge wave form. In addition, the peak amplitude of the magnet load recovery current exceeded design specifications. A SPICE analysis confirmed the suspected mechanisms for the parasitic ringing and the excessive load current {open_quotes}undershoot{close_quotes}. This paper will address the subsequent analysis, measurements, and modifications carried out during the maintenance shutdown in June 1993.

  16. Planetary rings: Structure and history

    NASA Astrophysics Data System (ADS)

    Esposito, L.

    The composition and structure of planetary rings provide the key evidence to understand their origin and evolution. Before the first space observations, we were able to maintain an idealized view of the rings around Saturn, the only known ring system at that time. Rings were then discovered around Jupiter, Uranus and Neptune. Saturn's F ring was discovered by Pioneer 11. Our ideal view of circular, planar, symmetric and unchanging rings was shattered by observations of inclined, eccentric rings, waves and wavy edges, and numerous processes acting at rates that give timescales much younger than the solar system. Moons within and near the rings sculpt them and are the likely progenitors of future rings. The moonlet lifetimes are much less than Saturn's age. The old idea of ancient rings gave rise to youthful rings, that are recently created by erosion and destruction of small nearby moons. Although this explanation may work well for most rings, Saturn's massive ring system provides a problem. It is extremely improbable that Saturn's rings were recently created by the destruction of a moon as large as Mimas, or even by the breakup of a large comet that passed too close to Saturn. The history of Saturn's rings has been a difficult problem, now made even more challenging by the close-up Cassini measurements. Cassini observations show unexpected ring variability in time and space. Time variations are seen in ring edges, in the thinner D and F rings, and in the neutral oxygen cloud, which outweighs the E ring in the same region around Saturn. The rings are inhomogeneous, with structures on all scales, sharp gradients and edges. Compositional gradients are sharper than expected, but nonetheless cross structural boundaries. This is evidence for ballistic transport that has not gone to completion. The autocovariance maximizes in the middle of the A ring, with smaller structure near the main rings' outer edge. Density wave locations have a fresher ice composition. The

  17. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  18. Edge-on Look at Saturn's Rings

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronomers are studying the unusual appearance of Saturn's rings. The top portion of this Hubble Space Telescope snapshot shows Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted, but because the Earth was almost in the plane of Saturn's rings, they appear edge-on. Positioned above the ring plane, the Sun is causing the rings to cast a shadow on Saturn. The bottom photograph shows Saturn with its rings slightly tilted, and displays a faint narrow ring, the F-ring, just outside the main ring, which is normally invisible from Earth. The moon called Dion, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting of the sun on the ring plane.

  19. Particle properties and processes in Uranus' rings

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Brahic, A.; Burns, J. A.; Marouf, Essam A.

    1991-01-01

    The particle properties and processes in the Uranian rings are analyzed from Voyager observations and ground-based data. Occultation observations of the epsilon ring are interpreted to yield an effective size of the ring particles that exceeds 70 cm, a surface mass density that exceeds 80 g/sq cm, and a ring vertical thickness greater than tens of meters for solid ice particles. The particles forming the classic rings are dark and gray, with albedo of 0.014 +/-0.004. It is argued that the small amount of dust that exists in the classical rings and between the rings in bands is created by erosion of ring particles and unseen satellites resulting from collisions and micrometeoroid bombardment. As proposed for regions of the other known ring systems, new ring material can be continually created by the destruction of small moons near the rings, which may explain the youthful appearance of the Uranian rings.

  20. Transition between different quantum states in a mesoscopic system: The superconducting ring

    SciTech Connect

    Horane, E.M.; Castro, J.I.; Buscaglia, G.C.; Lopez, A.

    1996-04-01

    We investigate the thermodynamic properties of a superconducting ring, both analytically and numerically, relying upon the Ginzburg-Landau theory. We find that modulated solutions for the order parameter play a role in describing the thermodynamic transitions between consecutive modes of uniform order parameter, associated with different quantum numbers. Exact expressions for these solutions are given in terms of elliptic functions. We identify the family of energy extrema which, being saddle points of the energy in the functional space of the distributions of the order parameter, represent the energy barrier to be overcome for transitions between different solutions. {copyright} {ital 1996 The American Physical Society.}

  1. Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Schoerling, Daniel; Antoniou, Fanouria; Bernhard, Axel; Bragin, Alexey; Karppinen, Mikko; Maccaferri, Remo; Mezentsev, Nikolay; Papaphilippou, Yannis; Peiffer, Peter; Rossmanith, Robert; Rumolo, Giovanni; Russenschuck, Stephan; Vobly, Pavel; Zolotarev, Konstantin

    2012-04-01

    To achieve high luminosity at the collision point of the Compact Linear Collider (CLIC), the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 and 4 nm before the beams enter the 1.5 TeV linear accelerators. An effective way to accomplish ultralow emittances with only small effects on the electron polarization is using damping rings operating at 2.86 GeV equipped with superconducting wiggler magnets. This paper describes a technical design concept for the CLIC damping wigglers.

  2. A silicon photonics circuit based on micro-ring resonators in the instantaneous frequency measurement system

    NASA Astrophysics Data System (ADS)

    Wang, Wanjun; Zhou, Jie; Wang, Jun; Feng, Junbo; Guo, Jin

    2015-10-01

    In this paper, a compact silicon photonics circuit is proposed. It consists of add-drop filter, input/output grating coupler. The resonance peak of add-drop filter can be tuned with the assist of p-i-n diode. The unknown frequency of microwave is loaded at the optical wave and coupled into the chip. The optical power ratio of through port and drop port is monotonous, which is corresponding to the unknown frequency. Meanwhile, the resonance peak of the ring can shift with the assist of p-i-n diode.

  3. A practical systems engineering process for integrating SSC collider ring components

    SciTech Connect

    Simmons, J.Y.

    1991-03-01

    Successful development and integration of the Superconducting Super Collider (SSC) collider rings requires coordination of unique design implementations formulated by the SSC Laboratory organizations, and later by individual superconducting magnet and spool piece manufacturers. Application of the Interface Control Working Group/Interface Control Document process provides a systematic review and concurrence of these designs, while minimizing constraints on the design process by avoiding excessively detailed specification. Design details necessary for integration of the separate components are documented and reviewed, with only inconsistencies and exceptions being addressed by management direction and/or specification revision. 7 figs.

  4. Spin-dependent ringing and beats in a quantum dot system

    NASA Astrophysics Data System (ADS)

    Souza, Fabrício M.

    2007-11-01

    We report spin-dependent quantum coherent oscillations (ringing) and beats of the total and the spin currents flowing through a quantum dot with Zeeman split levels. The spin-dependent transport is calculated via nonequilibrium Green function in the transient after a bias voltage is turned on at t=0 . The dot is coupled to two electrodes that can be ferromagnetic or nonmagnetic. In the ferromagnetic case both parallel and antiparallel alignments are considered. The coherent oscillation and beat frequencies are controlled via the Zeeman energy EZ . In particular, for EZ=0 no beats are observed and the spin current is zero for nonmagnetic leads. In the ferromagnetic case a finite spin current is found for EZ=0 . The effects of temperature are also analyzed. We observe that with increasing temperature the ringing response and the beats tend to disappear. Additionally, the spin current goes to zero for nonmagnetic leads, remaining finite in the ferromagnetic case. The tunnel magnetoresistance also reveals quantum coherent oscillations and beats, and it attains negative values for small enough temperatures and short times.

  5. Toward a noninvasive automatic seizure control system in rats with transcranial focal stimulations via tripolar concentric ring electrodes.

    PubMed

    Makeyev, Oleksandr; Liu, Xiang; Luna-Munguía, Hiram; Rogel-Salazar, Gabriela; Mucio-Ramirez, Samuel; Liu, Yuhong; Sun, Yan L; Kay, Steven M; Besio, Walter G

    2012-07-01

    Epilepsy affects approximately 1% of the world population. Antiepileptic drugs are ineffective in approximately 30% of patients and have side effects. We are developing a noninvasive, or minimally invasive, transcranial focal electrical stimulation system through our novel tripolar concentric ring electrodes to control seizures. In this study, we demonstrate feasibility of an automatic seizure control system in rats with pentylenetetrazole-induced seizures through single and multiple stimulations. These stimulations are automatically triggered by a real-time electrographic seizure activity detector based on a disjunctive combination of detections from a cumulative sum algorithm and a generalized likelihood ratio test. An average seizure onset detection accuracy of 76.14% was obtained for the test set (n = 13). Detection of electrographic seizure activity was accomplished in advance of the early behavioral seizure activity in 76.92% of the cases. Automatically triggered stimulation significantly (p = 0.001) reduced the electrographic seizure activity power in the once stimulated group compared to controls in 70% of the cases. To the best of our knowledge this is the first closed-loop automatic seizure control system based on noninvasive electrical brain stimulation using tripolar concentric ring electrode electrographic seizure activity as feedback. PMID:22772373

  6. The Enceladus Ring

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] The Enceladus Ring (labeled)

    This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

    The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

    Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

    Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

    An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

    One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

    Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

  7. Commissioning results of the narrow-band beam position monitor system upgrade in the APS storage ring.

    SciTech Connect

    Singh, O.

    1999-04-20

    When using a low emittance storage ring as a high brightness synchrotron radiation source, it is critical to maintain a very high degree of orbit stability, both for the short term and for the duration of an operational fill. A fill-to-fill reproducibility is an additional important requirement. Recent developments in orbit correction algorithms have provided tools that are capable of achieving a high degree of orbit stability. However, the performance of these feedback systems can be severely limited if there are errors in the beam position monitors (BPMs). The present orbit measurement and correction system at the APS storage ring utilizes 360 broad-band-type BPMs that provide turn-by-turn diagnostics and an ultra-stable orbit: < 1.8 micron rms vertically and 4.5 microns rms horizontally in a frequency band of 0.017 to 30 Hz. The effects of beam intensity and bunch pattern dependency on these BPMs have been significantly reduced by employing offset compensation correction. Recently, 40 narrow-band switching-type BPMs have been installed in the APS storage ring, two in each of 20 operational insertion device straight sections, bringing the total number of beam position monitors to 400. The use of narrow-band BPM electronics is expected to reduce sensitivity to beam intensity, bunch pattern dependence, and long-term drift. These beam position monitors are used for orbit correction/feedback and machine protection interlocks for the insertion device beamlines. The commissioning results and overall performance for orbit stability are provided.

  8. Planetary ring dynamics and morphology

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Durisen, Richard H.; Shu, Frank H.

    1987-01-01

    Evidence for a moonlet belt in the region between Saturn's close-in moonrings Pandora and Prometheus is discussed. It is argued that little-known observations of magnetospheric electron density by Pioneer 11 imply substantial, ongoing injections of mass into the 2000 km region which surrounds the F ring. A hypothesis is presented that these events result naturally from interparticle collisions between the smaller members of an optically thin belt of moonlets. Also discussed is work on Uranus ring structure and photometry, image processing and analysis of the Jonian ring strucure, photometric and structural studies of the A ring of Saturn, and improvements to an image processing system for ring studies.

  9. Spiral waves in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    1989-01-01

    Spiral density waves and spiral bending waves have been observed at dozens of locations within Saturn's rings. These waves are excited by resonant gravitational perturbations from moons orbiting outside the ring system. Modeling of spiral waves yields the best available estimates for the mass and the thickness of Saturn's ring system. Angular momentum transport due to spiral density waves may cause significant orbital evolution of Saturn's rings and inner moons. Similar angular momentum transfer may occur in other astrophysical systems such as protoplanetary disks, binary star systems with disks and spiral galaxies with satellites.

  10. Analysis of longitudinal beam dynamics behavior and rf system operative limits at high-beam currents in storage rings

    NASA Astrophysics Data System (ADS)

    Mastorides, T.; Rivetta, C.; Fox, J. D.; van Winkle, D.; Teytelman, D.

    2008-06-01

    A dynamics simulation model is used to estimate limits of performance of the positron-electron project (PEP-II). The simulation captures the dynamics and technical limitations of the low level radio frequency (LLRF) system, the high-power rf components, and the low-order mode coupled-bunch longitudinal beam dynamics. Simulation results showing the effect of nonlinearities on the LLRF loops, and studies of the effectiveness of technical component upgrades are reported, as well as a comparison of these results with PEP-II measurements. These studies have led to the estimation of limits and determining factors in the maximum stored current that the low energy ring/high energy ring (LER/HER) can achieve, based on system stability for different rf station configurations and upgrades. In particular, the feasibility of the PEP-II plans to achieve the final goal in luminosity, which required an increase of the beam currents to 4 A for LER and 2.2 A for HER, is studied. These currents are challenging in part because they would push the longitudinal low-order beam mode stability to the limit, and the klystron forward power past a level of satisfactory margin. An acceptable margin is defined in this paper, which in turn determines the corresponding klystron forward power limitation.

  11. Ring Enlargement of Three-Membered Boron Heterocycles upon Reaction with Organic π Systems: Implications for the Trapping of Borylenes.

    PubMed

    Krasowska, Małgorzata; Bettinger, Holger F

    2016-07-18

    New low-energy pathways for the reaction between substituted boriranes and borirenes with unsaturated hydrocarbons (ethyne or ethene) were discovered using density functional and coupled cluster theory. The interaction between the π bond of the hydrocarbon and the empty p orbital of the boron center leads to ring expansion of the three-membered to a five-membered boron heterocycle. The reactions are strongly exothermic and have low or even no barriers. They involve intermediates with a pentacoordinate boron center with two hydrocarbon molecules coordinating to boron akin to metal-olefin complexes. These borylene complexes are shallow minima on the potential energy surfaces. But significantly higher barriers for ring formation are computed for 1,5-cyclooctadiene and dibenzocyclooctatetraene complexes of borylenes, making these complexes likely detectable under appropriate experimental conditions. Our computational findings have implications for the interpretation of trapping experiments of thermally generated small borylenes with excess of small π systems. Because of very low barriers for reactions of three-membered boron heterocycles with π systems and the at least locally large excess of the latter under such conditions, formation of five-membered boron heterocycles should be considered. PMID:27305278

  12. Flex-gear power transmission system for transmitting EMF between Sun and ring gears

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1994-01-01

    A plurality of flexible cylindrical members, termed flex-gears and having gear tooth type perimeters are located in an annular space between two concentric rotating gear members, one an inner gear member and the other an outer ring gear member, both of which have mutually facing toothed surfaces which engage the flex-gears. The flex-gears rotate and orbit around the annular space as planetary gears when the inner and outer gear members rotate with respect to one another. Pairs of these elements located in two mutually parallel planes and separated by insulators provide two electrical conductor paths across which an electrical signal source, AC or DC, can be connected and coupled to an electrical device. Alternatively, one set of elements including outer gears segmented into mutually insulated semicircles and inner gears segmented into mutually insulated quadrants can be used.

  13. Curvature sensing using an added-signal in a fiber optic cavity ring-down system

    NASA Astrophysics Data System (ADS)

    Silva, Susana O.; Biswas, P.; Bandyopadhyay, S.; Jorge, P. A.; Marques, M. B.; Frazão, O.

    2015-09-01

    This work presents a fiber-optic Cavity Ring-Down (CRD) configuration using an added-signal for curvature sensing. An Optical Time-Domain Reflectometer (OTDR) was used to send impulses down into the fiber loop cavity, inside of which a long period grating (LPG) was placed to act as sensing device. The added-signal was obtained by the sum of several conventional CRD impulses, thus providing an improvement on the curvature sensitivity when compared to the conventional CRD signal processing. Sensitivity to applied curvature of 15.3 μs/m-1 was obtained. This result was found to be 20-fold the one obtained for the conventional CRD signal processing.

  14. Phosphine-Catalyzed Enantioselective Intramolecular [3+2] Annulations To Generate Fused Ring Systems

    PubMed Central

    2015-01-01

    Substantial progress has been described in the development of asymmetric variants of the phosphine-catalyzed intermolecular [3+2] annulation of allenes with alkenes; however, there have not been corresponding advances for the intramolecular process, which can generate a higher level of complexity (an additional ring and stereocenter(s)). In this study, we describe the application of chiral phosphepine catalysts to address this challenge, thereby providing access to useful scaffolds that are found in bioactive compounds, including diquinane and quinolin-2-one derivatives, with very good stereoselectivity. The products of the [3+2] annulation can be readily transformed into structures that are even more stereochemically rich. Mechanistic studies are consistent with β addition of the phosphepine to the allene being the turnover-limiting step of the catalytic cycle, followed by a concerted [3+2] cycloaddition to the pendant olefin. PMID:25815702

  15. Reagent-based DOS: developing a diastereoselective methodology to access spirocyclic- and fused heterocyclic ring systems.

    PubMed

    Damerla, V Surendra Babu; Tulluri, Chiranjeevi; Gundla, Rambabu; Naviri, Lava; Adepally, Uma; Iyer, Pravin S; Murthy, Y L N; Prabhakar, Nampally; Sen, Subhabrata

    2012-10-01

    Herein, we report a diversity-oriented-synthesis (DOS) approach for the synthesis of biologically relevant molecular scaffolds. Our methodology enables the facile synthesis of fused N-heterocycles, spirooxoindolones, tetrahydroquinolines, and fused N-heterocycles. The two-step sequence starts with a chiral-bicyclic-lactam-directed enolate-addition/substitution step. This step is followed by a ring-closure onto the built-in scaffold electrophile, thereby leading to stereoselective carbocycle- and spirocycle-formation. We used in silico tools to calibrate our compounds with respect to chemical diversity and selected drug-like properties. We evaluated the biological significance of our scaffolds by screening them in two cancer cell-lines. In summary, our DOS methodology affords new, diverse scaffolds, thereby resulting in compounds that may have significance in medicinal chemistry. PMID:22887684

  16. Flex-gear power transmission system for transmitting EMF between Sun and ring gears

    NASA Astrophysics Data System (ADS)

    Vranish, John M.

    1994-10-01

    A plurality of flexible cylindrical members, termed flex-gears and having gear tooth type perimeters are located in an annular space between two concentric rotating gear members, one an inner gear member and the other an outer ring gear member, both of which have mutually facing toothed surfaces which engage the flex-gears. The flex-gears rotate and orbit around the annular space as planetary gears when the inner and outer gear members rotate with respect to one another. Pairs of these elements located in two mutually parallel planes and separated by insulators provide two electrical conductor paths across which an electrical signal source, AC or DC, can be connected and coupled to an electrical device. Alternatively, one set of elements including outer gears segmented into mutually insulated semicircles and inner gears segmented into mutually insulated quadrants can be used.

  17. Saturn's E ring

    NASA Technical Reports Server (NTRS)

    Baum, W. A.; Kreidl, T.; Westphal, J. A.; Danielson, G. E.; Seidelmann, P. K.; Pascu, D.; Currie, D. G.

    1981-01-01

    Observations of the tenuous E ring of Saturn made by an earth-based CCD system at the time of the ring-plane crossing of March 1980 are presented. The observations were made with the CCD system attached to the 1.8-m Perkins reflector at Lowell Observatory using a pupil mask behind a focal plane mask to suppress telescopic diffraction. Photometric analysis of the CCD images reveal the edge-on brightness profile of the ring, beginning at a distance of 3 Saturn radii, to peak sharply in the vicinity of the orbit of Enceladus at about 4 Saturn radii, then decrease to a distance of over 8 Saturn radii. In addition, beyond Enceladus, the edge-on width of the ring is observed to increase with radial distance, reaching nearly 5 arcsec at 7 Saturn radii. Observations suggest, on the one hand, that the E ring is associated with Enceladus and possibly represents material ejected from the satellite, and on the other, that the ring is at an early stage in its evolution.

  18. Structure, function and clinical relevance of the cardiac conduction system, including the atrioventricular ring and outflow tract tissues.

    PubMed

    Dobrzynski, Halina; Anderson, Robert H; Atkinson, Andrew; Borbas, Zoltan; D'Souza, Alicia; Fraser, John F; Inada, Shin; Logantha, Sunil J R J; Monfredi, Oliver; Morris, Gwilym M; Moorman, Anton F M; Nikolaidou, Thodora; Schneider, Heiko; Szuts, Viktoria; Temple, Ian P; Yanni, Joseph; Boyett, Mark R

    2013-08-01

    It is now over 100years since the discovery of the cardiac conduction system, consisting of three main parts, the sinus node, the atrioventricular node and the His-Purkinje system. The system is vital for the initiation and coordination of the heartbeat. Over the last decade, immense strides have been made in our understanding of the cardiac conduction system and these recent developments are reviewed here. It has been shown that the system has a unique embryological origin, distinct from that of the working myocardium, and is more extensive than originally thought with additional structures: atrioventricular rings, a third node (so called retroaortic node) and pulmonary and aortic sleeves. It has been shown that the expression of ion channels, intracellular Ca(2+)-handling proteins and gap junction channels in the system is specialised (different from that in the ordinary working myocardium), but appropriate to explain the functioning of the system, although there is continued debate concerning the ionic basis of pacemaking. We are beginning to understand the mechanisms (fibrosis and remodelling of ion channels and related proteins) responsible for dysfunction of the system (bradycardia, heart block and bundle branch block) associated with atrial fibrillation and heart failure and even athletic training. Equally, we are beginning to appreciate how naturally occurring mutations in ion channels cause congenital cardiac conduction system dysfunction. Finally, current therapies, the status of a new therapeutic strategy (use of a specific heart rate lowering drug) and a potential new therapeutic strategy (biopacemaking) are reviewed. PMID:23612425

  19. The Orbits of the Uranian Satellites and Rings, the Gravity Field of the Uranian System, and the Orientation of the Pole of Uranus

    NASA Astrophysics Data System (ADS)

    Jacobson, R. A.

    2014-11-01

    French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson & Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques. Government sponsorship acknowledged.

  20. The orbits of the uranian satellites and rings, the gravity field of the uranian system, and the orientation of the pole of Uranus

    SciTech Connect

    Jacobson, R. A.

    2014-11-01

    French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson and Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques.

  1. System test of an optoelectronic gyroscope based on a high Q-factor InP ring resonator

    NASA Astrophysics Data System (ADS)

    Dell'Olio, Francesco; Indiveri, Fabrizio; Innone, Filomena; Dello Russo, Pasquale; Ciminelli, Caterina; Armenise, Mario N.

    2014-12-01

    The experimental results of the system test of an optical resonant passive gyroscope based on a high Q-factor ring resonator in InP technology are reported. The open loop configuration based on the phase modulation was preferred among the analyzed configuration options, especially because it is potentially suitable for the monolithic integration of the entire sensor on a single chip. The setup components are described with a special emphasis on a custom digital readout board based on a field-programmable gate array. The board processes the input signals according to the proportional-integral algorithm which has been implemented through an optimized firmware. For the system test, the sensor rotation has been simulated using two properly driven acousto-optic modulators. The results reported here prove the gyro functionality and are a good starting point for the full development of the sensor.

  2. Design of the Vacuum System for the High Energy Ring of an Asymmetric B-Factory Based on PEP

    SciTech Connect

    Barletta, W.

    2005-04-08

    The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. They present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 Gev electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high photon flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in < 500 hr of operation.

  3. Experimental investigation of thermal processes in the multi-ring Couette system with counter rotation of cylinders

    NASA Astrophysics Data System (ADS)

    Mamonov, V. N.; Nazarov, A. D.; Serov, A. F.; Terekhov, V. I.

    2016-01-01

    The effect of parameters of the multi-ring Couette system with counter rotating coaxial cylinders on the process of thermal energy release in a viscous liquid filling this system is considered with regard to the problem of determining the possibility of creating the high-performance wind heat generator. The multi-cylinder rotor design allows directly conversion of the mechanical power of a device consisting of two "rotor" wind turbines with a common axis normal to the air flow into the thermal energy in a wide range of rotational speed of the cylinders. Experimental results on the measurement of thermal power released in the pilot heat generator at different relative angular speeds of cylinder rotation are presented.

  4. In-situ calibration: migrating control system IP module calibration from the bench to the storage ring

    SciTech Connect

    Weber, Jonah M.; Chin, Michael

    2002-04-30

    The Control System for the Advanced Light Source (ALS) at Lawrence Berkeley National Lab (LBNL) uses in-house designed IndustryPack(registered trademark) (IP) modules contained in compact PCI (cPCI) crates with 16-bit analog I/O to control instrumentation. To make the IP modules interchangeable, each module is calibrated for gain and offset compensation. We initially developed a method of verifying and calibrating the IP modules in a lab bench test environment using a PC with LabVIEW. The subsequent discovery that the ADCs have significant drift characteristics over periods of days of installed operation prompted development of an ''in-situ'' calibration process--one in which the IP modules can be calibrated without removing them from the cPCI crates in the storage ring. This paper discusses the original LabVIEW PC calibration and the migration to the proposed in-situ EPICS control system calibration.

  5. Surface Composition of the Non-Ice Component on Icy Satellites and Ring Particles in the Saturn System

    NASA Astrophysics Data System (ADS)

    Clark, R. N.; Pearson, N.; Perlman, Z. S.; Bradley, E. T.; Hendrix, A.; Cuzzi, J. N.; Cruikshank, D. P.; Filacchione, G.; Nicholson, P. D.; Hedman, M. M.; Brown, R. H.; Buratti, B. J.; Baines, K. H.; Sotin, C.; Nelson, R.

    2013-12-01

    Saturn's icy satellites and ring particle surfaces have long been known to be composed mostly of frozen water. However, all surfaces show an absorption due to a non-water-ice component whose identity has not been well understood. In the near infrared, water ice has strong absorptions which limit detectability of other trace components. Similarly, at wavelengths less than about 0.18 microns, water is very absorbing. However, in the ~0.2 to ~1 micron range, water ice has low absorption and trace components are readily detected. Classical interpretations of the UV absorber and dark material on outer Solar System satellites have been varying amounts of tholins and carbon. However, tholins have spectral structure not seen in the icy spectra in the Saturn System. Many silicates also have UV spectral structure that reject them from contributing significantly to the observed spectral signatures. We have constructed a new UV spectrometer and a new environment chamber for studying the spectral properties of materials from 0.1 to 15 microns. In our survey of the spectral properties of materials so far, we find that small amounts of metallic iron and iron oxides in the icy surfaces are compatible with and can explain the UV, visible and near-infrared spectra of icy surfaces in the Saturn system (0.12 to 5.1 microns) using data from the Cassini UltraViolet Imaging Spectrograph (UVIS) and the Visual and Infrared Mapping Spectrometer (VIMS). The wide range of observed UV-NIR (0.1-5 micron) spectral signatures provide strong constraints on composition and grain size distribution, including grain sizes of the ice. Spectra of the Saturnian rings and icy satellites indicate they have a large range of ice grain sizes, from tens of microns to sub-micron. Sub-micron ice grains create unusual spectral properties, which are seen in the spectra of the rings and satellites of Saturn and on satellites further out in the Solar System. Clark et al. (2012, Icarus v218, p831) showed that VIMS

  6. Compact and broadband circularly polarized ring antenna with wide beam-width for multiple global navigation satellite systems

    NASA Astrophysics Data System (ADS)

    Zhang, Hong-Lin; Hu, Bin-Jie; Zhang, Xiu-Yin

    2012-02-01

    A compact and broadband circularly polarized (CP) annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems (GNSS) in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width (HPBW) is 113° in both the x—z and y—z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.

  7. Ring Galaxies

    NASA Astrophysics Data System (ADS)

    Dennefeld, M.; Materne, J.

    1980-09-01

    Among the 338 exotic, intriguing and/or fascinating objects contained in Arp's catalogue of peculiar galaxies, two, Arp 146 and 147, are calling special attention as a presumably separate class of objects displaying closed rings with almost empty interior. It is difficult to find out when, historically speaking, attention was called first to this type of object as a peculiar class, but certainly ga1axies with rings were widely found and recognized in the early sixties, ul}der others by Vorontsov-Velyaminov (1960), Sandage (1961) in the Hubble Atlas or de Vaucouleurs (1964) in the first reference catalogue of ga1axies. The most recent estimates by Arp and Madore (1977) from a search on about 200 Schmidt plates covering 7,000 square degrees give 3.6 per cent of ring galaxies among 2,784 peculiar galaxies found. However, despite the mythological perfection associated with a circle, some ordering is necessary before trying to understand the nature of such objects. This is particularly true because a large fraction of those galaxies with rings are probably normal spiral galaxies of type RS or S(r) as defined by de Vaucouleurs, where the spiral arms are simply "closing the circle". A good example of such "ordinary" galaxy is NGC 3081 in the Hubble Atlas .

  8. Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

    SciTech Connect

    Furukawa, M.

    2014-01-15

    Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium are studied analytically and numerically, where the plasma is confined by only poloidal magnetic field generated by an internal ring current. The plasma current due to finite pressure can be divided into two components; one remains at isotropic pressure and the other arises from pressure anisotropy. When p{sub ⊥}, the pressure perpendicular to the magnetic field, is larger than p{sub ∥}, the pressure parallel to the magnetic field, those two components of plasma current tend to cancel each other to reduce the total amount of plasma current. Equilibrium beta limit is also examined, where the beta is a ratio of the plasma pressure to the magnetic pressure. The equilibrium beta limit decreases as the pressure anisotropy becomes strong. The beta value is strictly limited by ellipticity of the equilibrium equation when p{sub ∥}>p{sub ⊥}. On the other hand, when p{sub ⊥}>p{sub ∥}, although the tendency of the beta limit agrees with the ellipticity condition of the equilibrium equation, equilibria with a hyperbolic region can be obtained by iterative procedure with practically reasonable convergence criteria.

  9. Study of photon–magnon coupling in a YIG-film split-ring resonant system

    SciTech Connect

    Bhoi, B.; Aiyar, R.; Cliff, T.; Maksymov, I. S.; Kostylev, M.; Venkataramani, N.; Prasad, S.; Stamps, R. L.

    2014-12-28

    By using the stripline Microwave Vector–Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium–iron–garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9% at 3 GHz. Theoretically, we propose an equivalent circuit model of the SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetisation dynamics in the YIG film driven by the microwave currents in the SRR. The results obtained with the equivalent-circuit model are in good agreement with the experiment. This model provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in nonlinear and magnetically tuneable metamaterials exploiting the strong coupling of magnons to microwave photons.

  10. Mini-beta superconducting quadrupole magnet system for the TRISTAN main ring

    SciTech Connect

    Endo, K.; Tsuchiya, K.; Ohuchi, N.; Morita, Y.; Egawa, K.; Sugahara, R.; Fukuma, H.; Kabe, A.; Kubo, T.; Ohsawa, Y. )

    1992-01-01

    After several years of developing a superconducting magnet system (QCS system), including a cryogenic system, mini-beta magnets were installed at all interaction points during the summer of 1990. The final tests were continued until the end of January, 1991, followed immediately by beam operation. In this paper performances of QCS magnets and cryogenic systems are mainly described.

  11. Development of Real-time Erosion Monitoring System for Hall Thrusters by Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naoji; Tao, Lei; Yalin, Azer P.

    Sputter monitoring system using continuous-wave cavity ring-down spectroscopy (cw-CRDS) was built for both lifetime assessment and contamination effects in Hall thrusters. We have performed measurements of sputtered manganese atoms from acceleration channel wall (stainless steel 316) in an anode layer type Hall thruster. The measurement strategy is based upon detection of manganese atoms via an absorption line from ground state at a wavelength of 403.076 nm. The path-integrated number density is 1.4 ± 0.3 ×1013 m-2 at a discharge voltage of 200 V and an argon mass flow rate of 70 sccm. The number density is proportional to the discharge voltage, as expected. The number density and mass-loss have a relatively linear dependence. These results show the validity of the erosion sensor for Hall thruster lifetime estimation.

  12. Flexure-Ring for Centering a Concave Lens in a Bore of a Housing for an Optical System

    NASA Technical Reports Server (NTRS)

    Ford, Virginia G. (Inventor)

    2002-01-01

    A flexure-ring is provided for centering a lens in a bore of a housing with 3N lens contacting stubs, where N is an integer equal to or greater than one. The stubs are formed by increasing the inside diameter of the ring made to fit tightly around a lens except at 3N locations for the aforesaid stubs, and said ring having an outside diameter made to fit tightly inside the housing bore locations. Behind each stub, a segment of the ring is removed down to a chord perpendicular to a ring diameter passing through the center of each stub. That chord is selected to have a length greater than the lens contacting surface of the stub, thereby to produce a reduced cross section of the ring on both sides of the stub to serve as flexures in relieving stresses due to different coefficients of thermal expansion of the three parts involved due to changes in temperature while in use.

  13. Removal of copper and iron by polyurethane foam column in FIA system for the determination of nickel in pierced ring.

    PubMed

    Vongboot, Monnapat; Suesoonthon, Monrudee

    2015-01-01

    Polyurethane foam (PUF) mini-column was used to eliminate copper and iron for the determination of nickel in pierced rings. The PUF mini-column was connected to FIA system for on-line sorption of copper and iron in complexes form of CuSCN(+) and FeSCN(2+). For this season, the acid solution containing a mixture of Ni(II), Fe(III), Cu(II) and SCN(-) ions was firstly flew into the PUF column. Then, the percolated solution which Fe(III) and Cu(II) ions is separated from analysis was injected into FIA system to react with 4-(2-pyridylazo) resorcinol (PAR) reagent in basic condition which this method is called pH gradient technique. The Ni-PAR complexes obtained were measured theirs absorbance at 500 nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400 mmol/L KSCN and entirely to eliminate in acidic condition at pH 3.0. In the optimum condition of these experiments, the method provided the linear relationship between absorbance and the concentration of Ni(II) in the range from 5.00 to 30.00 mg/L. Linear equation is y=0.0134x+0.0033 (R(2)=0.9948). Precision, assessed in the term of the relative standard deviation, RSD, and accuracy for multiple determinations obtained in values of 0.77-1.73% and 97.4%, respectively. The level of an average amount of Ni(II) in six piercing rings was evaluated to be 14.78 mg/g. PMID:25281109

  14. MHD stability in a nonparaxial open system with ring-shaped mirrors

    SciTech Connect

    Arsenin, V.V.

    1988-03-01

    The flute stability of a low-pressure plasma in a system containing end confinement systems, formed on the side away from the axis, in necks with a divergent magnetic flux, is analyzed. When a confinement system of this sort is combined with a ''steep'' mirror system in which a certain layer is stable with respect to the ''first'' flute mode, stability is achieved for all modes.

  15. Positron ring system using anger-type detectors. Progress report, January 1-December 31, 1986

    SciTech Connect

    Muehllehner, G.

    1986-09-01

    The design of a new multislice system consisting of six position-sensitive area detectors has been completed, and the system is now in the final assembly phase. This system will be able to reconstruct a volume 50 cm in diameter and 10 cm long with equal resolution of 4 to 5 mm in all directions. The system achieves high sensitivity through a large acceptance angle which is made possible through the use of three-dimensional reconstruction algorithms.

  16. Design of a three-axis magnetic field measurement system for the magnetic shield of the ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Rong, Chuiyu; Yao, Xu

    2015-10-01

    The magnetic field is one of the main causes of zero drift in a Ring Laser Gyroscope (RLG), which should be avoided by adopting a magnetic shielding system. The Gauss Meter is usually used to measure the magnetic shielding effectiveness. Generally, the traditional Gauss Meter has advantages of high measure range and high reliability, however, its drawbacks such as complex structure, high price and the PC client software cannot be customized at will, are also obvious. In this paper, aiming at a type of experimental magnetic shielding box of RLG, we design a new portable three-axis magnetic field measurement system. This system has both high modularity degree and reliability, with measuring range at ±48Gs, max resolution at 1.5mGs and can measure the magnetic field in x, y and z direction simultaneously. Besides, its PC client software can be easily customized to achieve the automatic DAQ, analysis, plotting and storage functions. The experiment shows that, this system can meet the measuring requirements of certain type of experimental magnetic shielding box for RLG, meanwhile, for the measurement of some other magnetic shielding effectiveness, this system is also applicable.

  17. Synthetic approaches to the bicyclo[2.2.2]diazaoctane ring system common to the paraherquamides, stephacidins and related prenylated indole alkaloids.

    PubMed

    Miller, Kenneth A; Williams, Robert M

    2009-11-01

    The bicyclo[2.2.2]diazaoctane ring system is common to a number of highly biologically active secondary metabolites isolated from numerous species of fungi. In this tutorial review, we describe the varied synthetic approaches that have been employed to construct this ring system in the course of recent total synthesis endeavors, and this review should be of interest to synthetic organic chemists and natural product chemists. Detailed herein are a number of synthetic disconnections including intramolecular S(N)2' cyclizations, biomimetic Diels-Alder reactions, radical cyclizations, and cationic cascade reactions. PMID:19847349

  18. Orbits of nine Uranian rings

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; French, R. G.; Frogel, J. A.; Elias, J. H.; Mink, D. J.; Liller, W.

    1981-01-01

    Observations of a stellar occultation by Uranus and its nine rings are presented and used to examine the structures and kinematics of the rings. The observations of the occultation of the K giant star KM 12 were obtained in the K band with the 4-m CTIO telescope at a signal-to-noise ratio higher than any previously obtained. Ring occultation profiles reveal the alpha ring to possibly have a double structure and less abrupt boundaries than the gamma ring, which exhibits diffraction fringes, while the eta ring is a broad ring with an unresolved narrow component at its inner edge. The present timing data, as well as previous occultation timings, are fit to a kinematic model in which all nine rings are treated as coplanar eclipses of zero inclination, precessing due to the zonal harmonics of the Uranian gravitational potential to obtain solutions for the ring orbits. Analysis of the residuals from the fitted orbits reveals that the proposed model is a good representation of ring kinematics. The reference system defined by the orbit solutions has also been used to obtain a value of 0.022 + or - 0.003 for the ellipticity of Uranus and a Uranian rotation period of 15.5 h.

  19. From nerve net to nerve ring, nerve cord and brain--evolution of the nervous system.

    PubMed

    Arendt, Detlev; Tosches, Maria Antonietta; Marlow, Heather

    2016-01-01

    The puzzle of how complex nervous systems emerged remains unsolved. Comparative studies of neurodevelopment in cnidarians and bilaterians suggest that this process began with distinct integration centres that evolved on opposite ends of an initial nerve net. The 'apical nervous system' controlled general body physiology, and the 'blastoporal nervous system' coordinated feeding movements and locomotion. We propose that expansion, integration and fusion of these centres gave rise to the bilaterian nerve cord and brain. PMID:26675821

  20. Cavity ring-down spectroscopy with an automated control feedback system for investigating nitrate radical surface chemistry reactions

    NASA Astrophysics Data System (ADS)

    Flemmer, Michael M.; Ham, Jason E.

    2012-08-01

    Nitrate radical (NO3•) surface chemistry of indoor environments has not been well studied due to the difficulty in generating and maintaining NO3• at low concentrations for long term exposures. This article presents the Surface Chemistry Reactant Air Delivery and Experiment System (SCRADES), a novel feedback controlled system developed to deliver nitrate radicals at specified concentrations (50-500 ppt, ±30 ppt) and flow rates (500-2000 ml min-1) to a variety of indoor surfaces to initiate reaction chemistry for periods of up to 72 h. The system uses a cavity ring-down spectrometer (CRDS), with a detection limit of 1.7 ppt, to measure the concentration of NO3• supplied to a 24 l experiment chamber. Nitrate radicals are introduced via thermal decomposition of N2O5 and diluted with clean dry air until the desired concentration is achieved. Additionally, this article addresses details concerning NO3• loss through the system, consistency of the NO3• concentration delivered, and stability of the CRDS cavity over long exposure durations (72 h).

  1. Uranus' Rings: Leading up to RPX

    NASA Astrophysics Data System (ADS)

    de Pater, I.; Showalter, M.; Hammel, H.; Gibbard, S.; Lissauer, J.

    We summarize recent HST and Keck observations of the uranian ring system, taken over the past years while the viewing geometry is changing. Some highlights of our campaign to date include: i) Detection of a ring system outside of Uranus main ring system by HST (Showalter and Lissauer, Science 311, p.973, 2006), followed by color information from Keck (de Pater et al, Science 312, p.92, 2006). This system consists of two rings. The inner ring, U2, is red and relatively narrow like Saturn's G ring, while the outer ring, U1, is much broader in extent and very blue, like Saturn's E ring. Just like Enceladus is located within the E ring, moon Mab is inside U1. Saturn's E ring is most likely produced by geyser activity on Enceladus. Mab, being over 20 times smaller, is unlikely to be geologically active. However, being this small, its size is optimal to produce a ring via meteorite sputtering. ii) Detection of a ring interior to the main ring system, which might be ring 1986U2R, discovered by Voyager, though its extent and location is different from the Voyager ring. iii) Dust sheets in between the main ring. These may be similar to the dust sheets seen by Voyager in forward scattered light, yet our observations indicate large changes from the Voyager era iv) New moons were detected by HST. The orbits of some of these moons appear to be somewhat erratic. The color of moon Mab appears to be more similar to that of the large outer moons than the small inner moons. Earth will cross Uranus' ring plane three times in 2007-2008 (2 May, 16 Aug. 2007, 20 Feb. 2008), and the Sun will cross it once (7 Dec. 2007). At these times optically thin dusty rings will brighten considerably, making this period an ideal time to study Uranus' outer ring system. Between the May and August crossings, as well as between December and February, the Earth and Sun are on opposite sides of the rings, so that any optically thick rings will essentially be invisible. This allows phenomena normally

  2. Reversible photoswitching of rotaxane character and interplay of thermodynamic stability and kinetic lability in a self-assembling ring-axle molecular system.

    PubMed

    Baroncini, Massimo; Silvi, Serena; Venturi, Margherita; Credi, Alberto

    2010-10-11

    We have designed, synthesized, and investigated a self-assembling system that can be reversibly interconverted between thermodynamically stable (pseudorotaxane) and kinetically inert (rotaxane) forms by light irradiation. The system is composed of a dibenzo[24]crown-8 ring and an axle comprised of a dibenzylammonium recognition site and two azobenzene end groups. The isomeric form of the azobenzene units of the axle has a little influence on the stability constants of the respective pseudorotaxanes but greatly affects the threading-dethreading rate constants. In fact, equilibration of the ring and the axle in its EE isomeric form occurs within seconds in acetonitrile at room temperature, whereas the ZZ axle threads-dethreads the ring at least four orders of magnitude slower. Moreover, we show that a change in the stability of the complex, achieved by deprotonating the dibenzylammonium recognition site on the axle, affects its kinetic behavior. We compare the results of these experiments with those observed upon dethreading the (pseudo)rotaxane by using a competitive guest for the ring, an approach which does not inherently destabilize the ring-axle interaction. This study outlines a general strategy for the reversible photochemical control of motion kinetics in threaded and interlocked compounds and constitutes a starting point for the construction of multicomponent structures that can behave as photochemically driven nanomachines. PMID:20842670

  3. The Structure of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Colwell, J. E.; Nicholson, P. D.; Tiscareno, M. S.; Murray, C. D.; French, R. G.; Marouf, E. A.

    of accretion and disruption at the edges of Saturn's Roche zone. Clumps and strands form and are disrupted as they encounter each other and are perturbed by close encounters with nearby Prometheus. The menagerie of structures in the rings reveals a system that is dynamic and evolving on timescales ranging from days to tens or hundreds of millions of years. The architecture of the rings thus provides insight to the origin as well as the long and short-term evolution of the rings.

  4. Gravitomagnetic field of rotating rings

    NASA Astrophysics Data System (ADS)

    Ruggiero, Matteo Luca

    2016-04-01

    In the framework of the so-called gravitoelectromagnetic formalism, according to which the equations of the gravitational field can be written in analogy with classical electromagnetism, we study the gravitomagnetic field of a rotating ring, orbiting around a central body. We calculate the gravitomagnetic component of the field, both in the intermediate zone between the ring and the central body, and far away from the ring and central body. We evaluate the impact of the gravitomagnetic field on the motion of test particles and, as an application, we study the possibility of using these results, together with the Solar System ephemeris, to infer information on the spin of ring-like structures.

  5. A low-cost dielectric spectroscopic system using metamaterial open horn-ring resonator-inspired BSF and detection circuitry

    NASA Astrophysics Data System (ADS)

    Kumari, Ratnesh; Patel, Piyush N.

    2016-07-01

    The sensitivity in a lower microwave band dielectric spectroscopic system is relatively less compared to that of millimeter wave and terahertz system. This work reports modeling and development of an epsilon-negative metamaterial resonator-inspired microwave band-stop filter as a prototype device and its detection circuitry for the spectroscopic analysis of dielectric samples in S-band. The device structure consists of a diamond-shaped patch with a complementary open split horn-ring resonator, fabricated on a Neltech substrate of relative permittivity ( ɛ r = 3.2). The measured transmission coefficient at 2.2 GHz and simulated result at 2.24 GHz demonstrate an excellent accuracy in the device fabrication. A low-cost connector-type microwave signal detection system was assembled for the real-time transduction of device signal into an equivalent DC voltage. Further, a single channel cavity developed using polydimethylsiloxane was placed over the resonator gap for analyzing the perturbation effect of electric field intensity on the resonance and circuit output DC level for different dielectric samples under test. The performed calibrations show linearity up to 82.5 % in the device response.

  6. A microcomputer-based data acquisition and control system for the direct shear, ring shear, triaxial shear, and consolidation tests

    USGS Publications Warehouse

    Powers, Philip S.

    1983-01-01

    This report is intended to provide internal documentation for the U.S. Geological Survey laboratory's automatic data acquisition system. The operating procedures for each type of test are designed to independently lead a first-time user through the various stages of using the computer to control the test. Continuing advances in computer technology and the availability of desktop microcomputers with a wide variety of peripheral equipment at a reasonable cost can create an efficient automated geotechnical testing environment. A geotechnical testing environment is shown in figure 1. Using an automatic data acquisition system, laboratory test data from a variety of sensors can be collected, and manually or automatically recorded on a magnetic device at the same apparent time. The responses of a test can be displayed graphically on a CRT in a matter of seconds, giving the investigator an opportunity to evaluate the test data, and to make timely, informed decisions on such matters as whether to continue testing, abandon a test, or modify procedures. Data can be retrieved and results reported in tabular form, or graphic plots, suitable for publication. Thermistors, thermocouples, load cells, pressure transducers, and linear variable differential transformers are typical sensors which are incorporated in automated systems. The geotechnical tests which are most practical to automate are the long-term tests which often require readings to be recorded outside normal work hours and on weekends. Automation applications include incremental load consolidation tests, constant-rate-of-strain consolidation tests, direct shear tests, ring shear tests, and triaxial shear tests.

  7. Castro ring zone: a 4,500-km2 fossil hydrothermal system in the Challis volcanic field, central Idaho.

    USGS Publications Warehouse

    Criss, R.E.; Ekren, E.B.; Hardyman, R.F.

    1984-01-01

    The largest fossil hydrothermal system occupying a 4500 km2 area in central Idaho is revealed by delta 18O studies. The remains of this meteoric-hydrothermal system are preserved within a sharply bounded, 15 km wide, 70-km-diameter annulus of low delta 18O rock (+2.0 to -8.8per mille) termed the Castro ring zone. The zone is centred on a less depleted (+4.5) core zone consisting of granitic rocks of the Castro pluton. This 700-km2 Eocene subvolcanic batholith has intruded, domed, and hydrothermally metamorphosed a thick sequence of Challis Volcanics, the stratigraphically low rocks in the 2000-km2 Van Horn Peak and the 1000-km2 Thunder Mountain cauldron complexes being most strongly altered. Less extreme 18O depletions occur in the youngest major ash-flow sheets of these complexes, indicating a vertical 18O gradient. Water/rock ratios of geothermal systems are surprisingly insensitive to the circulation scale.-L.-di H.

  8. How Jupiter's Ring Was Discovered.

    ERIC Educational Resources Information Center

    Elliot, James; Kerr, Richard

    1985-01-01

    "Rings" (by astronomer James Elliot and science writer Richard Kerr) is a nontechnical book about the discovery and exploration of ring systems from the time of Galileo to the era of the Voyager spacecraft. One of this book's chapters is presented. (JN)

  9. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  10. An active interlock system for the NSLS x-ray ring insertion devices

    SciTech Connect

    Nawrocky, R.J.; Biscardi, R.; Dabrowski, J.; Flannigan, J.; Ramamoorthy, S.; Rothman, J.; Smith, J.; So, I.; Thomas, M. ); Decker, G. )

    1991-01-01

    This paper describes the design and operation of an active interlock system which has been installed in the NSLS X-ray electron storage ing to protect the vacuum chamber from thermal damage by mis-steered high power photon beams from insertion devices (IDs). the system employs active beam position detectors to monitor beam motion in the ID straight sections and solid state logic circuitry to dump'' the stored beam in the event of a fault condition by interrupting the rf. To ensure a high degree of reliability, redundancy and continuous automatic checking has been incorporated into the design. Overall system integrity is checked periodically with beam at safe levels of beam current. 2 refs., 3 figs.

  11. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  12. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  13. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David R.

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receive a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  14. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2000-01-01

    An all-refelctive optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six refelecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  15. Many-body dynamics of a Bose system with attractive interactions on a ring

    SciTech Connect

    Li Weibin; Xie Xiaotao; Yang Xiaoxue; Zhan Zhiming

    2005-10-15

    We investigate the many-body dynamics of an effectively attractive one-dimensional Bose system confined in a toroidal trap. The mean-field theory predicts that a bright-soliton state will be formed when the interparticle interaction increases over a critical point. The study of quantum many-body dynamics in this paper reveals that there is a modulation instability in a finite Bose system correspondingly. We show that Shannon entropy becomes irregular near and above the critical point due to quantum correlations. We also study the dynamical behavior of the instability by exploring the momentum distribution and the fringe visibility, which can be verified experimentally by releasing the trap.

  16. Full-configuration-interaction study of the metal-insulator transition in model systems: Peierls dimerization in H(n) rings and chains.

    PubMed

    Giner, Emmanuel; Bendazzoli, Gian Luigi; Evangelisti, Stefano; Monari, Antonio

    2013-02-21

    The Peierls dimerization with associated metal-insulator transition is studied in a model systems with ab initio methods. These are chains and rings H(N) of hydrogen atoms treated by full CI using a minimal STO-3G atomic orbital basis for N = 6 to N = 14. We describe and discuss in some detail the potential energy surface governing Peierls' dimerization and study the localization tensor as the indicator of the metal-insulator transition. Results for linear chains and rings are compared. PMID:23445017

  17. Experiments with a New, Unique Large-Scale Rig Investigating the Effects of Background System Rotation on Vortex Rings in Water

    NASA Astrophysics Data System (ADS)

    Brend, Mark A.; Verzicco, Roberto

    2005-11-01

    We introduce our unique, new large-scale experimental facility [1] designed for our long-term research program investigating the effects of background system rotation on the stability and the dynamics of vortex rings. The new rig constitutes a large water-filled tank positioned on a rotating turntable and its overall height and diameter are 5.7m and 1.4 m, respectively. First experimental and computational results of our program are summarized. We will show various videos of flow visualizations that illustrate some major, qualitative differences between rings propagating in rotating and non-rotating flows. Some of the investigated characteristics of the vortex rings include their translation velocity, the velocity field inside and surrounding the rings, and, in particular, their stability. We will briefly outline experiments employing the relatively new Ultrasonic-Velocity-Profiler technique (UVP). This technique appears to be particularly suited for some of our measurements and it was, as far as we are aware, not previously used in the context of vortex-ring studies. [1] http://www.eng.warwick.ac.uk/staff/pjt/turntabpics/voriskt.html

  18. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  19. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Weve recently discovered narrow sets of rings around two minor planets orbiting in our solar system. How did these rings form? A new study shows that they could be a result of close encounters between the minor planets and giants like Jupiter or Neptune.Unexpected Ring SystemsPositions of the centaurs in our solar system (green). Giant planets (red), Jupiter trojans (grey), scattered disk objects (tan) and Kuiper belt objects (blue) are also shown. [WilyD]Centaurs are minor planets in our solar system that orbit between Jupiter and Neptune. These bodies of which there are roughly 44,000 with diameters larger than 1 km have dynamically unstable orbits that cross paths with those of one or more giant planets.Recent occultation observations of two centaurs, 10199 Chariklo and 2060 Chiron, revealed that these bodies both host narrow ring systems. Besides our four giant planets, Chariklo and Chiron are the only other bodies in the solar system known to have rings. But how did these rings form?Scientists have proposed several models, implicating collisions, disruption of a primordial satellite, or dusty outgassing. But a team of scientists led by Ryuki Hyodo (Paris Institute of Earth Physics, Kobe University) has recently proposed an alternative scenario: what if the rings were formed from partial disruption of the centaur itself, after it crossed just a little too close to a giant planet?Tidal Forces from a GiantHyodo and collaborators first used past studies of centaur orbits to estimate that roughly 10% of centaurs experience close encounters (passing within a distance of ~2x the planetary radius) with a giant planet during their million-year lifetime. The team then performed a series of simulations of close encounters between a giant planet and a differentiated centaur a body in which the rocky material has sunk to form a dense silicate core, surrounded by an icy mantle.Some snapshots of simulation outcomes (click for a closer look!) for different initial states of

  20. Mu-28: an open-framework fluorogallophosphate with a three-dimensional 12-membered ring channel system

    SciTech Connect

    Josien, Ludovic; Simon-Masseron, Angelique . E-mail: a.simon@univ-mulhouse.fr; Gramlich, Volker; Porcher, Florence; Patarin, Jogl

    2004-10-01

    A new three-dimensional (3-D) microporous fluorogallophosphate, named Mu-28, was obtained by hydrothermal synthesis. It was obtained in the presence of fluoride ions with 1,4-dimethylpiperazine as organic template. This new fluorogallophosphate, with chemical formula [Ga{sub 20}P{sub 20}O{sub 80}(OH){sub 6}F{sub 6}(H{sub 2}O){sub 4}(C{sub 6}H{sub 16}N{sub 2}){sub 6}] 8H{sub 2}O, crystallizes in the monoclinic system space group P2{sub 1} with the following unit cell parameters: a=13.23(1)A, b=15.40(1)A, c=14.80(1)A, {beta}=95.10(9){sup o} (Z=1, R1=0.0435 [I>2{sigma}(I)]). Its structure was determined by single-crystal X-ray diffraction with the help of {sup 31}P NMR spectroscopy. Mu-28 consists of a complex arrangement of GaO{sub 3}(OH,F)(H{sub 2}O){sub 2}, GaO{sub 4}(OH)F and GaO{sub 4}(OH){sub 2} octahedra, GaO{sub 4}F trigonal bipyramids and GaO{sub 3}(OH,F) and PO{sub 4} tetrahedra. It displays a 3-D channel system delimited by 12-membered ring openings.

  1. Ground Movement in SSRL Ring

    SciTech Connect

    Sunikumar, Nikita; /UCLA /SLAC

    2011-08-25

    Users of the Stanford Synchrotron Radiation Lightsource (SSRL) are being affected by diurnal motion of the synchrotron's storage ring, which undergoes structural changes due to outdoor temperature fluctuations. In order to minimize the effects of diurnal temperature fluctuations, especially on the vertical motion of the ring floor, scientists at SSRL tried three approaches: painting the storage ring white, covering the asphalt in the middle of the ring with highly reflective Mylar and installing Mylar on a portion of the ring roof and walls. Vertical motion in the storage ring is measured by a Hydrostatic Leveling System (HLS), which calculates the relative height of water in a pipe that extends around the ring. The 24-hr amplitude of the floor motion was determined using spectral analysis of HLS data, and the ratio of this amplitude before and after each experiment was used to quantitatively determine the efficacy of each approach. The results of this analysis showed that the Mylar did not have any significant effect on floor motion, although the whitewash project did yield a reduction in overall HLS variation of 15 percent. However, further analysis showed that the reduction can largely be attributed to a few local changes rather than an overall reduction in floor motion around the ring. Future work will consist of identifying and selectively insulating these local regions in order to find the driving force behind diurnal floor motion in the storage ring.

  2. Double-ring network model of the head-direction system

    NASA Astrophysics Data System (ADS)

    Xie, Xiaohui; Hahnloser, Richard H.; Seung, H. Sebastian

    2002-10-01

    In the head-direction system, the orientation of an animal's head in space is encoded internally by persistent activities of a pool of cells whose firing rates are tuned to the animal's directional heading. To maintain an accurate representation of the heading information when the animal moves, the system integrates horizontal angular head-velocity signals from the vestibular nuclei and updates the representation of directional heading. The integration is a difficult process, given that head velocities can vary over a large range and the neural system is highly nonlinear. Previous models of integration have relied on biologically unrealistic mechanisms, such as instantaneous changes in synaptic strength, or very fast synaptic dynamics. In this paper, we propose a different integration model with two populations of neurons, which performs integration based on the differential input of the vestibular nuclei to these two populations. We mathematically analyze the dynamics of the model and demonstrate that with carefully tuned synaptic connections it can accurately integrate a large range of the vestibular input, with potentially slow synapses.

  3. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  4. Saturn's Rings Edge-on

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.

    For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.

    The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.

    This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).

    Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science

  5. Practical synthesis and cytotoxic evaluation of the pyrazino[1,2-b]-isoquinoline ring system.

    PubMed

    Hernández-Vázquez, Eduardo; Miranda, Luis D

    2016-06-01

    A practical three-step protocol for the synthesis of pyrazino[1,2-b]isoquinolines is reported. This approach includes a one-pot parallel cyclization/cyclization parallel process followed by a non-common 6-endo Heck cyclization that transformed previously constructed Ugi adducts into diversely decorated tricyclic systems. Compounds bearing a t-butyl or 2,6-dimethylphenyl substituent showed significant cytotoxic activity. The most active analogue (6p) showed significant activity against HCT-15 and K562 (IC50 = 41.8 ± 3.3 and 57.7 ± 2.1 μM, respectively) with no cytotoxicity against human gingival fibroblasts. PMID:27161451

  6. Compact stellar systems in the polar ring galaxies NGC 4650A and NGC 3808B: Clues to polar disk formation

    NASA Astrophysics Data System (ADS)

    Ordenes-Briceño, Yasna; Georgiev, Iskren Y.; Puzia, Thomas H.; Goudfrooij, Paul; Arnaboldi, Magda

    2016-01-01

    Context. Polar ring galaxies (PRGs) are composed of two kinematically distinct and nearly orthogonal components, a host galaxy (HG) and a polar ring/disk (PR). The HG usually contains an older stellar population than the PR. The suggested formation channel of PRGs is still poorly constrained. Suggested options are merger, gas accretion, tidal interaction, or a combination of both. Aims: To constrain the formation scenario of PRGs, we study the compact stellar systems (CSSs) in two PRGs at different evolutionary stages: NGC 4650A with well-defined PR, and NGC 3808 B, which is in the process of PR formation. Methods: We use archival HST/WFPC2 imaging in the F450W, F555W, or F606W and F814W filters. Extensive completeness tests, PSF-fitting techniques, and color selection criteria are used to select cluster candidates. Photometric analysis of the CSSs was performed to determine their ages and masses using stellar population models at a fixed metallicity. Results: Both PRGs contain young CSSs (<1 Gyr) with masses of up to 5 × 106M⊙, mostly located in the PR and along the tidal debris. The most massive CSSs may be progenitors of metal-rich globular clusters or ultra compact dwarf (UCD) galaxies. We identify one such young UCD candidate, NGC 3808 B-8, and measure its size of reff = 25.23+1.43-2.01 pc. We reconstruct the star formation history of the two PRGs and find strong peaks in the star formation rate (SFR, ≃200 M⊙/yr) in NGC 3808 B, while NGC 4650 A shows milder (declining) star formation (SFR< 10 M⊙/yr). This difference may support different evolutionary paths between these PRGs. Conclusions: The spatial distribution, masses, and peak star formation epoch of the clusters in NGC 3808 suggest for a tidally triggered star formation. Incompleteness at old ages prevents us from probing the SFR at earlier epochs of NGC 4650 A, where we observe the fading tail of CSS formation. This also impedes us from testing the formation scenarios of this PRG.

  7. Synthesis and Characterization of High Performance Polyimides Containing the Bicyclo(2.2.2)oct-7-ene Ring System

    NASA Technical Reports Server (NTRS)

    Alvarado, M.; Harruna, I. I.; Bota, K. B.

    1997-01-01

    Due to the difficulty in processing polyimides with high temperature stability and good solvent resistance, we have synthesized high performance polyimides with bicyclo(2.2.2)-oct-7-ene ring system which can easily be fabricated into films and fibers and subsequently converted to the more stable aromatic polyimides. In order to improve processability, we prepared two polyimides by reacting 1,4-phenylenediamine and 1,3phenylediamine with bicyclo(2.2.2)-7-octene-2,3,5,6-tetracarboxylic dianhydride. The polyimides were characterized by FTIR, FTNMR, solubility and thermal analysis. Thermogravimetric analysis (TGA) showed that the 1,4-phenylenediamine and 1,3-phenylenediamine containing polyimides were stable up to 460 and 379 C, respectively under nitrogen atmosphere. No melting transitions were observed for both polyimides. The 1,4-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, methane sulfonic acid and soluble in sulfuric acid at room temperature. The 1,3-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, tetramethyl urea, N,N-dimethyl acetamide and soluble in methane sulfonic acid and sulfuric acid.

  8. A novel FPGA-based bunch purity monitor system at the APS storage ring.

    SciTech Connect

    Norum, W. E.; APS Engineering Support Division

    2008-01-01

    Bunch purity is an important source quality factor for the magnetic resonance experiments at the Advanced Photon Source. Conventional bunch-purity monitors utilizing time-to-amplitude converters are subject to dead time. We present a novel design based on a single field- programmable gate array (FPGA) that continuously processes pulses at the full speed of the detector and front-end electronics. The FPGA provides 7778 single-channel analyzers (six per rf bucket). The starting time and width of each single-channel analyzer window can be set to a resolution of 178 ps. A detector pulse arriving inside the window of a single-channel analyzer is recorded in an associated 32-bit counter. The analyzer makes no contribution to the system dead time. Two channels for each rf bucket count pulses originating from the electrons in the bucket. The other four channels on the early and late side of the bucket provide estimates of the background. A single-chip microcontroller attached to the FPGA acts as an EPICS IOC to make the information in the FPGA available to the EPICS clients.

  9. Synthesis and biological evaluation of some polymethoxylated fused pyridine ring systems as antitumor agents.

    PubMed

    Rostom, Sherif A F; Hassan, Ghada S; El-Subbagh, Hussein I

    2009-10-01

    A series of 3,5-bis(arylidene)-4-piperidones like chalcone analogues carrying variety of methoxylated aryl groups, pyrazolo[4,3-c]pyridines, pyrido[4,3-d]pyrimidines, and pyrido[3,2-c]pyridines, carrying an arylidene moiety, and some pyrano[3,2-c]pyridines, like flavone and coumarin isosteres, were synthesized and screened for their in-vitro antitumor activity at the National Cancer Institute (NCI, USA). The tested compounds 7, 9, 10, 12, 13, 15, 17, and 19 exhibited a broad spectrum of antitumor activity. Compounds belonging to the pyrazolo[4,3-c]pyridine series proved to be more active than those of the pyrido[3,2-c]pyridine and pyrano[3,2-c]pyridine analogues, in which the monomethoxylated derivatives showed better antitumor activity when compared with their corresponding dimethoxylated congeners. Compound 7 is considered to be the most active member identified in this study with a broad spectrum of activity against 22 different tumor cell lines belonging to the nine subpanels employed, and a particular effectiveness against the breast cancer T-47D cell line (GI 54.7%). The pyrano[3,2-c]pyridine heterocyclic system 19 proved to be the most active antitumor agent among the six-membered fused pyridines, with variable activity against 18 different tumor cell lines, and special activity against the non-small cell lung cancer Hop-92 and ovarian cancer OVCAR-4 cell lines (GI values 63.9 and 48.5%, respectively). PMID:19714673

  10. Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system

    NASA Astrophysics Data System (ADS)

    Martín, J. C.; Berdejo, V.; Vallés, J. A.; Sánchez-Martín, J. A.; Díez, A.; Andrés, M. V.

    2013-10-01

    We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C-1 was achieved in CW operation. Then, by means of parameters obtained by numerically fitting the experimental results, the potential sensing performance of the laser configuration with an SCF as a TDA is studied. Moreover, two ring cavity laser configurations (with the SCF acting basically as an attenuator or also as the active media) are compared and the influence of the position of the coupler inside the ring cavity and the contribution of the erbium doping to improve the sensor features are analysed. The longer interaction lengths compatible with laser action using the Er-doped SCF as a TDA could provide variations of laser output power up to 8.6% °C-1 for 90 mW pump power and a 1 m methanol-filled SCF.

  11. A survey of candidate missions to explore Saturn's rings

    NASA Technical Reports Server (NTRS)

    Wells, W. C.; Price, M. J.

    1972-01-01

    The ring system around Saturn is discussed. Exploration of the rings is required for an understanding of their origin and the hazard they represent to spacecraft near Saturn. In addition the rings may provide useful clues to the origin of the solar system. This study examines the problem of ring system exploration and recommends a sequence of missions which will collect the data required.

  12. A bisphenol-A-based resin system that cures via triazole ring formation for marine composite applications

    NASA Astrophysics Data System (ADS)

    Gorman, Irene Elizabeth

    Large composite panels, such as those utilized in marine applications, cannot be economically cured in an autoclave. For these structures the elevated temperatures necessary to achieve high crosslink density must come from the curing reaction itself. We are developing a resin system that cures via triazole ring formation (cycloaddition reaction of azides with terminal alkynes) instead of the traditional oxirane/amine reaction. The high exothermicity of the azido/alkyne reaction is expected to yield higher extents of reaction under ambient-cure conditions, making the resin system potentially suitable for "out-of-autoclave" curing processes. This work was conducted through a multi-tiered approach involving synthesis, kinetic studies, thermal characterization, and mechanical analysis. The difunctional azide-terminated resin, di(3-azido-2 hydroxypropyl) ether of bisphenol-A (DAHP-BPA), was selected as the baseline diazide. A number of alkyne crosslinkers were synthesized and characterized, including propiolate esters of di- and trifunctional alcohols, propargyl esters of di- and trifunctional carboxylic acids, propargyl ethers of di- and trifunctional alcohols, and N,N,N',N'-tetrapropargyl derivatives of primary diamines. Commercially available tripropargylamine (TPA) was also studied. Curing energetics as a function of alkyne type and catalyst loading, investigated through a dynamic differential scanning calorimetry approach, displayed two distinct kinetic profiles when considering propiolate and propargyl type crosslinkers. Those systems employing a propiolate-based alkyne were found to be much more reactive towards the Huisgen 1,3-dipolar cycloaddition than the propargyl species. Additionally, the mechanical and thermal properties of resin systems, both un-catalyzed and catalyzed, composed of DAHP-BPA and tripropargyl amine were investigated by compression and rheological studies, differential scanning calorimetry, and thermogravametric analysis. The moduli of both

  13. Belt-hierarchic structure of th ring, satellite and planet systems: prediction S/2001 U1 and others objects in Solar system

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2003-04-01

    BELT-HIERARCHIC STRUCTURE OF THE RING, SATELLITE AND PLANET SYSTEMS: PREDICTION S/2001 U1 AND OTHERS OBJECTS IN SOLAR SYSTEM Yu.V.Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Structure regularities of the planet and satellite systems have been studied. Statistic analysis of the distribution of the major semi-axes of the orbits of the planets, comets and centaurs of the Solar system, satellite and ring systems of Jupiter, Saturn, Neptune and Uran, exoplanet systems of the pulsars PSR 1257+12, PSR 1828-11 and of the main consequence star Ups And was fulfilled. The following empirical regularities were described [1]: 1) the bodies of systems are combined into hierarchic groups and main from them combine 5 companions; 2) differences of the major semi-axes of the neighboring orbits for bodies of every group are constant; 4) for main neighboring hierarchic group these distances are distinguished in 6 times increasing to external grope; 5) the filling of the gropes and some present changes in their structure are caused by the past catastrophes in corresponding systems. The special method of reconstruction of the catastrophes which had place in the life of the Solar system (SS) was developed. Suggested method has let us to explain uniformly observed values of the major semi-axes and average values of eccentricities of the planets. In particular the Pancul’s hypothesis about Jupiter formation from two giant protoplanets (Jupiter I and Jupiter II) was confirmed. The new empirical law of the filling of the orbits of the regular groups of the planets or satellites (or rings structures) of the hierarchic ordered systems of celestial bodies was established. It was shown that sum number of bodies is proportional to the value of catastrophic value of the eccentricities which are same for first, second ,.... and fifth orbits of all gropes. The theoretical numbers of bodies for pointed orbits practically coincide with their observed numbers in main

  14. Uranus and the shape of elliptical rings

    NASA Technical Reports Server (NTRS)

    Lucke, R. L.

    1978-01-01

    It is reported that when the star SAO158687 passed behind the Uranus system, its light was occulted twice by the epsilon (fifth) ring of the planet. The first part of the ring to occult was about 100 km wide and the second part was about 40 km wide. The variable width of the ring is accounted for by differences in the orbital eccentricities of the individual particles composing the ring.

  15. Saturn Ring Observer

    NASA Technical Reports Server (NTRS)

    Spilker, T. R.

    2001-01-01

    Answering fundamental questions about ring particle characteristics, and individual and group behavior, appears to require close-proximity (a few km) observations. Saturn's magnificent example of a ring system offers a full range of particle sizes, densities, and behaviors for study, so it is a natural choice for such detailed investigation. Missions implementing these observations require post-approach Delta(V) of approximately 10 km/s or more, so past mission concepts called upon Nuclear Electric Propulsion. The concept described here reduces the propulsive Delta(V) requirement to as little as 3.5 km/s, difficult but not impossible for high-performance chemical propulsion systems. Additional information is contained in the original extended abstract.

  16. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  17. A cavity ring-down spectroscopy system for high time resolution measurements of gaseous elemental mercury concentrations

    NASA Astrophysics Data System (ADS)

    Pierce, Ashley M.

    The global cycling of mercury (Hg), a highly toxic environmental pollutant, currently has many unknowns. There are various sources of Hg to the atmosphere including both anthropogenic and natural sources. Processes involved in the global cycling of Hg include emissions from legacy Hg pools, deposition, re-emission, and chemical and physical transformation processes such as gas-phase oxidation and heterogeneous redox reactions. Gaseous elemental mercury (GEM) can represent >95% of Hg present in the atmosphere. GEM has a relatively long atmospheric lifetime, which allows it to be transported 1000s of km, effectively making it a global pollutant. Once deposited, Hg can be converted to methylmercury, a bioavailable form of Hg known to cause neurological damage in wildlife and humans. Current atmospheric Hg sensors require long analyzing periods for a single sample (minutes to hours), thus a faster-response sensor would improve characterization of surface-atmosphere exchange processes and atmospheric Hg dynamics. The goal of this thesis work was to develop a new, field-deployable sensor for high time resolution measurements of GEM in ambient air using pulsed cavity ring-down spectroscopy (CRDS). In this research, a CRDS system was developed using a pulsed laser (50 Hz pulse repetition rate) emitting wavelengths tunable between 215 and 280 nm (Hg absorbs at 253.65 nm), a high finesse 1-m-long cavity lined with two high reflectivity mirrors. Due to the long path length (˜1 km) produced inside the short cavity, sample volumes could be kept small while measurement sensitivity remained high. By optimizing the CRDS setup and reducing interferences (e.g., ozone concentration fluctuations), the current CRDS sensor was deployed in the field to measure GEM concentrations in ambient air. The sensor was also used for the first-ever GEM flux measurements by the eddy covariance flux method. Results showed that fast GEM fluctuations could be detected by the CRDS sensor and the

  18. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration

    NASA Astrophysics Data System (ADS)

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-01

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of ˜60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of ˜170 mW at a wavelength of 1455 nm and a low EDFA pump power of ˜40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge.

  19. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.

    PubMed

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-15

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge. PMID:16936857

  20. Thermal emission from Saturn's rings at 380 microns

    SciTech Connect

    Roellig, T.L.; Werner, M.W.; Becklin, E.E.

    1988-03-01

    Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range. 24 references.

  1. Thermal emission from Saturn's rings at 380 microns

    NASA Technical Reports Server (NTRS)

    Roellig, Thomas L.; Werner, Michael W.; Becklin, Eric E.

    1988-01-01

    Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range.

  2. EDGE-ON VIEW OF SATURN'S RINGS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on. In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane. [bottom] - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys. Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn. The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2. CREDIT: Erich Karkoschka (University of Arizona Lunar and Planetary Lab) and NASA

  3. Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

    PubMed

    Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

    2016-06-01

    We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency. PMID:27155868

  4. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang

    2016-05-01

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ɛ-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ɛ-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  5. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  6. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  7. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  8. Spectroscopic studies, DFT calculations, and cytotoxic activity of novel silver(I) complexes of hydroxy ortho-substituted-nitro-2H-chromen-2-one ligands and a phenanthroline adduct.

    PubMed

    Mujahid, Muhammad; Kia, Agnieszka Foltyn-Arfa; Duff, Brian; Egan, Denise A; Devereux, Michael; McClean, Siobhán; Walsh, Maureen; Trendafilova, Natasha; Georgieva, Ivelina; Creaven, Bernadette S

    2015-12-01

    Silver(I) complexes of coumarin-based ligands and one of their phenanthroline (phen) adducts have been prepared and characterized using microanalytical data, molar conductivity, IR, (1)H and (13)C NMR, UV-Vis, and atomic absorption (AAS) spectroscopies. The binding modes of the coumarin-based ligands and the most probable structure of their Ag(I) complexes were predicted by means of molecular modeling and calculations of their IR, NMR, and absorption spectra using density functional theory (DFT). The cytotoxicity of the compounds studied against human-derived hepatic carcinoma cells (Hep-G2) and a renal cancer cell line (A498) showed that the complexes were more cytotoxic than the clinically used chemotherapeutic, mitoxantrone. The compounds showed little interaction with DNA and also did not show nuclease activity but manifested excellent superoxide dismutase activity which may indicate that their mechanism of action is quite different to many metal-based therapeutics. PMID:26492162

  9. Isotopic splitting patterns in the (13) C NMR spectra of some partially deuterated 1-aryl-2-(phenyldiazenyl)butane-1,3-dione and 4-hydroxy-3-(phenyldiazenyl)-2H-chromen-2-one: evidence for elucidation of tautomeric forms.

    PubMed

    Noroozi Pesyan, Nader; Rashidnejad, Hamid

    2016-05-01

    Nuclear magnetic resonance spectra of synthesized azo dyes derived from aniline derivatives in reaction with benzoylacetone and 4-hydroxycoumarin were studied in both CDCl3 and (CD3 )2 SO (two drops of D2 O were added into solutions of dyes). All dyes showed intramolecular hydrogen bonding. Dyes derived from o-nitro aniline in the reaction with benzoylacetone, and 4-hydroxycoumarin showed bifurcated intramolecular hydrogen bonds. The solvent-substrate proton exchange of dyes derived from benzoylacetone and 4-hydroxycoumarin was examined in the presence of two drops of D2 O. Among ten dye samples, two dyes derived from benzoylacetone did not show deuteration, three dyes showed partial deuteration and five dyes showed full deuteration under similar conditions. For the partially deuterated dyes the β-isotope effect in (13) C splitting was investigated and was used for the determination of the predominant tautomeric form. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26776053

  10. Euphorikanin A, a Diterpenoid Lactone with a Fused 5/6/7/3 Ring System from Euphorbia kansui.

    PubMed

    Fei, Dong-Qing; Dong, Le-Le; Qi, Feng-Ming; Fan, Gai-Xia; Li, Hui-Hong; Li, Zheng-Yu; Zhang, Zhan-Xin

    2016-06-17

    Euphorikanin A (1), an unprecedented diterpenoid lactone which possesses a novel 5/6/7/3-fused tetracyclic ring skeleton, was isolated from the roots of Euphorbia kansui. The chemical structure and absolute stereochemistry were elucidated on the basis of extensive spectroscopic methods and single-crystal X-ray diffraction analysis. Compound 1 exhibited moderate cytotoxicity against two human tumor cell lines HeLa and NCI-446. A proposed biosynthetic pathway of compound 1 is also described. PMID:27230557

  11. Self-Assembly of MinE on the Membrane Underlies Formation of the MinE Ring to Sustain Function of the Escherichia coli Min System*

    PubMed Central

    Zheng, Min; Chiang, Ya-Ling; Lee, Hsiao-Lin; Kong, Lih-Ren; Hsu, Shang-Te Danny; Hwang, Ing-Shouh; Rothfield, Lawrence I.; Shih, Yu-Ling

    2014-01-01

    The pole-to-pole oscillation of the Min proteins in Escherichia coli results in the inhibition of aberrant polar division, thus facilitating placement of the division septum at the midcell. MinE of the Min system forms a ring-like structure that plays a critical role in triggering the oscillation cycle. However, the mechanism underlying the formation of the MinE ring remains unclear. This study demonstrates that MinE self-assembles into fibrillar structures on the supported lipid bilayer. The MinD-interacting domain of MinE shows amyloidogenic properties, providing a possible mechanism for self-assembly of MinE. Supporting the idea, mutations in residues Ile-24 and Ile-25 of the MinD-interacting domain affect fibril formation, membrane binding ability of MinE and MinD, and subcellular localization of three Min proteins. Additional mutations in residues Ile-72 and Ile-74 suggest a role of the C-terminal domain of MinE in regulating the folding propensity of the MinD-interacting domain for different molecular interactions. The study suggests a self-assembly mechanism that may underlie the ring-like structure formed by MinE-GFP observed in vivo. PMID:24914211

  12. The modular structure of the inner-membrane ring component PrgK facilitates assembly of the type III secretion system basal body.

    PubMed

    Bergeron, Julien R C; Worrall, Liam J; De, Soumya; Sgourakis, Nikolaos G; Cheung, Adrienne H; Lameignere, Emilie; Okon, Mark; Wasney, Gregory A; Baker, David; McIntosh, Lawrence P; Strynadka, Natalie C J

    2015-01-01

    The type III secretion system (T3SS) is a large macromolecular assembly found at the surface of many pathogenic Gram-negative bacteria. Its role is to inject toxic "effector" proteins into the cells of infected organisms. The molecular details of the assembly of this large, multimembrane-spanning complex remain poorly understood. Here, we report structural, biochemical, and functional analyses of PrgK, an inner-membrane component of the prototypical Salmonella typhimurium T3SS. We have obtained the atomic structures of the two ring building globular domains and show that the C-terminal transmembrane helix is not essential for assembly and secretion. We also demonstrate that structural rearrangement of the two PrgK globular domains, driven by an interconnecting linker region, may promote oligomerization into ring structures. Finally, we used electron microscopy-guided symmetry modeling to propose a structural model for the intimately associated PrgH-PrgK ring interaction within the assembled basal body. PMID:25533490

  13. Two-image mosaic of Saturn's rings

    NASA Technical Reports Server (NTRS)

    1980-01-01

    This computer-assembled two-image mosaic of Saturn's rings, taken by NASA's Voyager 1 on Nov. 6, 1980 at a range of 8 million kilometers (5 million miles), shows approximately 95 individual concentric features in the rings. The extraordinarily complex structure of the rings is easily seen across the entire span of the ring system. The ring structure, once thought to be produced by the gravitational interaction between Saturn's satellites and the orbit of ring particles, has now been found to be too complex for this explanation alone. The 14th satellite of Saturn, discovered by Voyager 1, is seen (upper left) just inside the narrow F-ring, which is less than 150 kilometers (93 miles wide). The Voyager Project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

  14. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  15. Optimizing Thomson's jumping ring

    NASA Astrophysics Data System (ADS)

    Tjossem, Paul J. H.; Brost, Elizabeth C.

    2011-04-01

    The height to which rings will jump in a Thomson jumping ring apparatus is the central question posed by this popular lecture demonstration. We develop a simple time-averaged inductive-phase-lag model for the dependence of the jump height on the ring material, its mass, and temperature and apply it to measurements of the jump height for a set of rings made by slicing copper and aluminum alloy pipe into varying lengths. The data confirm a peak jump height that grows, narrows, and shifts to smaller optimal mass when the rings are cooled to 77 K. The model explains the ratio of the cooled/warm jump heights for a given ring, the reduction in optimal mass as the ring is cooled, and the shape of the mass resonance. The ring that jumps the highest is found to have a characteristic resistance equal to the inductive reactance of the set of rings.

  16. On semi ring bornologies

    NASA Astrophysics Data System (ADS)

    Imran, A. N.; Rakhimov, I. S.; Husain, Sh. K. Said

    2016-06-01

    Our main focus in this work is to introduce new structure bornological semi rings. This generalizes the theory of algebraic semi rings from the algebraic setting to the framework of bornological sets. We give basic properties for this new structure. As well as, We study the fundamental construction of bornological semi ring as product, inductive limits and projective limits and their extensions on bornological semi ring. Additionally, we introduce the category of bornological semi rings and study product and pullback (fiber product) in the category of bornological semi rings.

  17. Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Schneider, Glenn; Carson, Joseph; Debes, John H.; Gaspar, Andras; Henning, Thomas; Hines, Dean C.; Hinz, Philip; Jang-Condell, Hannah; Kuchner, Marc J.; Moro-Martin, Amaya; Perrin, Marshall D.; Rodigas, T. J.; Serabyn, Gene; Silverstone, Murray D.; Stark, Christopher C.; Tamura, Motohide; Weinberger, Alycia J.; Wisniewski, John P.; Konishi, Mihoko

    2016-01-01

    How do circumstellar (CS) disks evolve and form planetary systems? Is our solar system's two-component debris disk (DD) typical? Are planets implicated by evidence of dynamical stirring in disks? Are DD architectures correlated with stellar mass? To address these highly-compelling questions of fundamental astrophysical import, we obtained deep follow-up HST/STIS coronagraphic imagery of five intermediate-inclination ring-like DDs. By combining data from two coronagraphic apertures we obtain images with unprecedented clarity, sensitivity, and photometric efficacy. We discover a scattered light counterpart to the dust disk previously seen in the mid-IR only in HD 141569 A interior to the 2 rings previously imaged in scattered light. We also place refined optical limits on planets in that system. For HR 4796 A we detect outer nebulosity extending as far as 10 arc seconds from the star, and compare it with other systems with distant dust. We report on early stages of analysis for our other 3 program stars.

  18. Iron nanotube-silica composite (ZVI-S-PCAT modified silica composite) preparation, characterization and application as a recyclable catalytic system for 5-membered ring organic transformations.

    PubMed

    Kour, Gurpreet; Gupta, Monika; Vishwanathan, B; Thirunavukkarasu, K

    2015-09-01

    Iron nanotube silica composite have been synthesized and studied through particle-size analysis, FTIR, SEM-EDX, TEM, XRD, UV, VSM, TGA-DTA and XPS techniques. The application of nanoframeworks as sustainable recyclable catalytic systems has been observed for azole cyclic ring organic transformations. The good reaction yields and characterization through (1)H NMR, (13)C NMR and mass analysis support the performance of the nanoframeworks. We also present here the synthesis of two novel compounds. Also the prepared nanoframework has been observed to show soft magnetism which provides a scope to be used in sensing devices. PMID:26228908

  19. On the appearance of a system of ring vortices in the mixing layer of axially symmetric turbulent jets under acoustic action

    NASA Astrophysics Data System (ADS)

    Pimshtein, V. G.

    2016-07-01

    The shadow visualization method is applied to study the process of loss of stability of the mixing layer of a subsonic axially symmetric turbulent jet under longitudinal internal action of saw-tooth sound waves of finite amplitude. Such action leads to the formation of a system of ring vortices in the mixing layer at the frequency of its intrinsic instability. The interaction of the vortices can be accompanied by sound emission. A similar phenomenon is also observed in turbulent jets for small supercritical pressure fluctuations on a nozzle.

  20. Intrinsic structure in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  1. No evidence of rings around Neptune

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Mink, D. J.; Baron, R. L.; Dunham, E.; Pingree, J. E.; French, R. G.; Elias, J. H.; Liller, W.; Nicholson, P. D.; Jones, T. J.

    1981-01-01

    The results of two observations of stellar occultations of Neptune to determine if the planet has a ring system are reported. The sightings were made from Mt. Stromlo, Mauna Kea, and Cerro Tololo, noting that an equatorial ring would subtend only two arcsec of view. An upper accretion limit was defined to set the region around Neptune where rings, rather than satellites, could form. The intensities of the starlight from the two selected stars were recorded by photometers on magnetic tape during the occultation period. One of the stars did not occult, but passed through the entire region where a ring system might be present. No definitive evidence for rings was found, although an optical depth for a Neptunian ring was calculated at 0.07, with a width of more than 5 km and a radius of 31,400 km.

  2. A summary of laboratory testing performed to characterize and select an elastomeric O-ring material to be used in the redesigned solid rocket motors of the space transportation system

    NASA Technical Reports Server (NTRS)

    Turner, J. E.

    1993-01-01

    An elastomeric O-ring material is used in the joints of the redesigned solid motors (RSRM's) of the National Space Transportation System (NSTS). The selection of the O-ring material used in the RSRM's was a very thorough process that included efforts by NASA's Marshall Space Flight Center and the Langley Research Center, and the Thiokol Corporation. One of the efforts performed at MSFC was an extensive in-house laboratory test regime to screen potential O-ring materials and ultimately to characterize the elastomeric material that was chosen to be used in the RSRM's. The laboratory tests performed at MSFC are summarized.

  3. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  4. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-12-01

    Cassini UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by roughly π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime.

  5. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-10-01

    7/16/10 12:23 PM UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime. 7/16/10 12:23 PM 7/16/10 12:23 PM

  6. Future studies of planetary rings by space probes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1984-01-01

    Recent space probe observations of the rings of Jupiter and Saturn have furnished a substantial enhancement of the current understanding of the outer planets' rings. Voyager 2 offers further opportunities for the study of the Neptune and Uranus ring systems. The Galileo mission to Jupiter furnishes the first opportunity for long term space probe studies of a planetary ring system. It is suggested that an appropriately instrumented Saturn orbiter would not only provide a similar opportunity for the study of the Saturn rings, but may also be the only means by which to adequately address the nature of the diverse phenomena displayed by this prototypical planetary ring system.

  7. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  8. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 0.75 million km from Saturn on 12 November 1980. The kinks and braids of this tightly-constrained ring are visible along with the outer edge of the A Ring. JPL managed the Voyager Project for NASA's Office of Space Science.

  9. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  10. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  11. Archiving of Planetary Ring Data

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    2001-01-01

    Stellar occultation data provide our only Earth-based means of probing planetary rings at kilometer spatial resolution. The occultation data archive at MIT contains original data and analysis products of stellar occultations by the ring systems of the planets Jupiter, Saturn, Uranus, and Neptune observed by members of the group (and other groups) from 1977 to the present. During this time period, several media have been used to record and store the original and processed data: (1) chart records; (2) printed output, (3) audio reel tape; (4) audio cassette tape; (5) 7-track, 1/2-inch computer tape; (6) 9-track, 1/2-inch computer tape at 800, 1600, and 6250 bpi; (7) NOVA disk platters (2.5 and 5.0 Mbyte); (8) write once optical disks; (9) punched cards; and (10) read-write optical disks. With the rapid change of computer technology over this time period, some of these media have become not only obsolete, but nearly extinct. In particular, it has become nearly impossible to find any facilities that can still read 800 bpi tapes, which contain the only copies of several important data sets for the ring system of Uranus. In particular, we have an extensive ring data collection that includes data sets for the following Uranian ring occultations: U0, U11, U12, U13, U14, U25, U17, and U36.

  12. Dynamics of dust in Jupiter's gossamer rings

    NASA Astrophysics Data System (ADS)

    Hamilton, D.; Burns, J.; Krueger, H.; Showalter, M.

    2003-04-01

    Over the past several years, the Galileo spacecraft has drastically improved our knowledge of Jupiter's faint rings. We now know the system to be composed of a main ring 7000km wide whose inner edge blossoms into a vertically-extended halo, and a pair of gossamer rings, each one extending inward from a small moon. These moonlets, Thebe and Amalthea, have large orbital tilts and resulting vertical excursions of 1150km and 4300km, respectively. The vertical thicknesses of the two Gossamer rings accurately match these values, providing compelling evidence that the two small satellites act as the dominant sources of ring material. Ring Material is born during high speed impacts onto the moonlet surfaces, after which the material evolves inward under the action of a dissipative force, either Poynting-Robertson Drag or Resonant Charge Variations. The basic framework for the origin and evolution of the Gossamer Rings is well understood, but there are a few loose ends that are not so easily explained: i) an outward extension of the Thebe Ring, ii) the nature of the dissipative force. In this talk I will report my latest dynamical modeling of the Gossamer rings associated with Thebe and Amalthea, and will discuss how in-situ impact data collected by the Galileo dust detector during the first ever ring "fly-through" may help to resolve some of these and other outstanding issues.

  13. Note: Reliable, robust measurement system for trace moisture in gas at parts-per-trillion levels using cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Abe, Hisashi; Lisak, Daniel; Cygan, Agata; Ciuryło, Roman

    2015-10-01

    We report a simple, robust cavity ring-down spectroscopy system to reliably measure trace moisture in gases at parts-per-trillion (ppt) levels. The performance of the system was evaluated on the basis of experiments performed in a manner traceable to the International System of Units. The obtained result was in good agreement with the primary trace-moisture standard at 12 nmol/mol (12 ppb) in N2 in amount-of-substance fraction. Measurement capability of residual moisture in high-purity dry N2 at ˜130 pmol/mol (130 ppt) was demonstrated, and background noise of 5.3 × 10-12 cm-1 was attained, corresponding to a minimum detectable H2O of 5 pmol/mol (5 ppt).

  14. 5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells.

    PubMed

    Henry, Sean; Kidner, Ria; Reisenauer, Mary R; Magedov, Igor V; Kiss, Robert; Mathieu, Véronique; Lefranc, Florence; Dasari, Ramesh; Evidente, Antonio; Yu, Xiaojie; Ma, Xiuye; Pertsemlidis, Alexander; Cencic, Regina; Pelletier, Jerry; Cavazos, David A; Brenner, Andrew J; Aksenov, Alexander V; Rogelj, Snezna; Kornienko, Alexander; Frolova, Liliya V

    2016-09-14

    Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance. PMID:27218860

  15. Synthesis, characterization and catalytic activity of Ag-acidfuchsin nanohybrid system towards the ring opening polymerization of ε-caprolactone

    NASA Astrophysics Data System (ADS)

    Meenarathi, B.; Palanikumar, S.; Kannammal, L.; Anbarasan, R.

    2015-01-01

    The acidfuchsin (AF) decorated Ag nanoparticle (NP) was synthesized and its ability towards the ring opening polymerization (ROP) of ε-caprolactone (CL) was studied under N2 atmosphere at 160 °C in the presence of stannous octoate (SO) as a catalyst. Both the nanohybrid and nanocomposites were characterized by various analytical tools like Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, fluorescence spectroscopy, gel permeation chromatography (GPC), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The number of binding site from the fluorescence spectrum confirmed that all the functional groups present in AF might have been involved in the ROP of CL.

  16. Ring Dynamics Up Close With the Saturn Ring Observer

    NASA Astrophysics Data System (ADS)

    Spilker, T. R.; Abelson, R. D.; Shirley, J. H.; Spilker, L. J.

    2005-12-01

    The National Research Council's Solar System Exploration Decadal Survey identified a Saturn Ring Observer (SRO) mission concept as one of two "promising concepts for longer-term missions" to the outer solar system. The spacecraft would orbit Saturn in a (mildly) non-Keplerian orbit within a km or two of Saturn's ring plane. Details of dynamical processes in Saturn's rings, thought by some researchers to have important implications for the dynamics of protoplanetary disks, appear to be observable only in situ, by stationing an observing platform sufficiently close to the rings to observe and characterize the collisions of cm-size and larger particles. Larger-scale (up to a few km) processes, including clumping and agglomeration behavior strongly suggested by Cassini data, can also be observed from this vantage point and related to the behavior of individual particles. Direct insertion from approach into such a "ring hover" orbit requires a propulsive delta-V of ~10 km/s. This exceeds the feasible limits for post-launch chemical propulsion, so this approach is a candidate for fission-powered electric propulsion. But such systems are decades in the future. A nearer-term implementation could insert via aerocapture using Saturn's atmosphere and then propulsively circularize into the hover orbit. Post-aerocapture clean-up and circularization maneuvers could use a standard chemical propulsion system that provides a much more palatable (for chemical systems) delta-V of ~3.5 km/s. We evaluated a year-long science mission that would begin with insertion into the hover orbit at a Kronocentric radius of 110,000 km, moving weekly to a more distant radial location to view scientifically interesting parts of Saturn's A and B rings, eventually traversing ~20,000 km radially across the rings. A Radioisotope Power System (RPS) powers the orbiter, including multiple instruments and the rather capable telecommunications system needed to return a large data volume from Saturn. This

  17. Let Freedom Ring! Bulletin, 1937, No. 32

    ERIC Educational Resources Information Center

    Calhoun, Harold G.; Calhoun, Dorothy; Hatch, Roy W.; Cohen, Philip H.; Schramm, Rudolf

    1937-01-01

    This volume of "Let Freedom Ring!" contains the scripts of the 13 national broadcasts of the radio series of that name presented in the spring of 1937 over the national network of the Columbia Broadcast System. In "Let Freedom Ring!" you will find the courage, the struggle, the triumph of men and women who fought to win and safeguard liberties…

  18. Traceable Ring Signature

    NASA Astrophysics Data System (ADS)

    Fujisaki, Eiichiro; Suzuki, Koutarou

    The ring signature allows a signer to leak secrets anonymously, without the risk of identity escrow. At the same time, the ring signature provides great flexibility: No group manager, no special setup, and the dynamics of group choice. The ring signature is, however, vulnerable to malicious or irresponsible signers in some applications, because of its anonymity. In this paper, we propose a traceable ring signature scheme. A traceable ring scheme is a ring signature except that it can restrict “excessive” anonymity. The traceable ring signature has a tag that consists of a list of ring members and an issue that refers to, for instance, a social affair or an election. A ring member can make any signed but anonymous opinion regarding the issue, but only once (per tag). If the member submits another signed opinion, possibly pretending to be another person who supports the first opinion, the identity of the member is immediately revealed. If the member submits the same opinion, for instance, voting “yes” regarding the same issue twice, everyone can see that these two are linked. The traceable ring signature can suit to many applications, such as an anonymous voting on a BBS. We formalize the security definitions for this primitive and show an efficient and simple construction in the random oracle model.

  19. Sunset on Saturn's Rings

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This is a rare view of Saturn's rings seen just after the Sun has set below the ring plane, taken with the Hubble Space Telescope on Nov. 21, 1995.

    This perspective is unusual because the Earth is slightly above (2.7 degrees latitude) Saturn's rings and the Sun is below them. Normally we see the rings fully illuminated by the Sun.

    The photograph shows three bright ring features: the F Ring, the Cassini Division, and the C Ring (moving from the outer rings to the inner). The low concentration of material in these rings allows light from the Sun to shine through them. The A and B rings are much denser, which limits the amount of light that penetrates through them. Instead, they are faintly visible because they reflect light from Saturn's disk.

    Scientists believe that the F Ring is slightly warped because it disappears part way around on the right (West) side. Hubble's high resolution shows the that A Ring's shadow obscures part of the F ring (right).

    The image was assembled from 20 exposures taken with Wide Field Planetary Camera-2 over 8 hours.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  20. Storage ring development at the National Synchrotron Light Source

    SciTech Connect

    Krinsky, S.; Bittner, J.; Fauchet, A.M.; Johnson, E.D.; Keane, J.; Murphy, J.; Nawrocky, R.J.; Rogers, J.; Singh, O.V.; Yu, L.H.

    1991-09-01

    This report contains papers on the following topics: Transverse Beam Profile Monitor; Bunch Length Measurements in the VUV Storage Ring; Photoelectric Effect Photon Beam Position Monitors; RF Receivers for Processing Electron Beam Pick-up Electrode Signals; Real-Time Global Orbit Feedback Systems; Local Orbit Feedback; Active Interlock System for High Power Insertion Devices in the X-ray Ring; Bunch Lengthening Cavity for the VUV Ring; SXLS Storage Ring Design.

  1. Polarization Transitions in Quantum Ring Arrays

    NASA Astrophysics Data System (ADS)

    Roostaei, Bahman; Mullen, Kieran

    2003-03-01

    We investigate the theory of the collective behavior of arrays of narrow quantum rings, small conducting loops with a radius R such that the confinement energy Eq = hbar^2/2mR^2 is comparable to the Coulomb energy between rings E_c=e^2/D, where D is the ring separation. We consider the classical and quantum cases where each ring holds one electron and consider nearest neighbor interactions only. We find that in a linear array of quantum rings there is a spontaneous transition to an antiferroelectric groundstate as δ=E_c/Eq increases. This transition exist for both finite and infinite length arrays, and corresponds well with the groundstate of the classical problem. We determine the transition as a function δ and ɛ=D/R. This differs from the classical case when there are many electrons on each ring, where charge distribution on each ring is quadrapolar. In 2D arrays of quantum rings we find that there is a four-fold degenerate antiferroelectric striped groundstate for a range of ɛ and δ. This groundstate can be strongly perturbed by edge effects in finite size arrays. We discuss how these systems correspond to possible experiments in semiconductor ring arrays. This material is based on work supported by the National Science Foundation under Grant Nos. EPS-0132534, and NSF-MRSEC DMR-0080054.

  2. The Catalog of Southern Ringed Galaxies

    NASA Astrophysics Data System (ADS)

    Buta, R.

    1995-01-01

    The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensive compilation of diameters, axis ratios, relative bar position angles, and morphologies of inner and outer rings, pseudorings, and lenses in 3692 galaxies south of declination -17 deg. The purpose of the catalog is to evaluate the idea that these ring phenomena are related to orbital resonances with a bar or oval in galaxy potentials. The catalog is based on visual inspection of most of the 606 fields of the Science Research Council (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, and Palomar Sky surveys used as auxiliaries when needed for overexposed core regions. The catalog is most complete for SRC fields 1-303 (mostly south of declination -42 deg). In addition to ringed galaxies, a list of 859 mostly nonringed galaxies intended for comparison with other catalogs is provided. Other findings from the CSRG that are not based on statistics are the identification of intrinsic bar/ring misalignment; bars which underfill inner rings; dimpling of R'1 pseudorings; pointy, rectangular, or hexagonal inner or outer ring shapes; a peculiar polar-ring-related system; and other extreme examples of spiral structure and ring morphology.

  3. Pleiotropic and Epistatic Behavior of a Ring-Hydroxylating Oxygenase System in the Polycyclic Aromatic Hydrocarbon Metabolic Network from Mycobacterium vanbaalenii PYR-1

    PubMed Central

    Kweon, Ohgew; Kim, Seong-Jae; Kim, Dae-Wi; Kim, Jeong Myeong; Kim, Hyun-lee; Ahn, Youngbeom; Sutherland, John B.

    2014-01-01

    Despite the considerable knowledge of bacterial high-molecular-weight (HMW) polycyclic aromatic hydrocarbon (PAH) metabolism, the key enzyme(s) and its pleiotropic and epistatic behavior(s) responsible for low-molecular-weight (LMW) PAHs in HMW PAH-metabolic networks remain poorly understood. In this study, a phenotype-based strategy, coupled with a spray plate method, selected a Mycobacterium vanbaalenii PYR-1 mutant (6G11) that degrades HMW PAHs but not LMW PAHs. Sequence analysis determined that the mutant was defective in pdoA2, encoding an aromatic ring-hydroxylating oxygenase (RHO). A series of metabolic comparisons using high-performance liquid chromatography (HPLC) analysis revealed that the mutant had a lower rate of degradation of fluorene, anthracene, and pyrene. Unlike the wild type, the mutant did not produce a color change in culture media containing fluorene, phenanthrene, and fluoranthene. An Escherichia coli expression experiment confirmed the ability of the Pdo system to oxidize biphenyl, the LMW PAHs naphthalene, phenanthrene, anthracene, and fluorene, and the HMW PAHs pyrene, fluoranthene, and benzo[a]pyrene, with the highest enzymatic activity directed toward three-ring PAHs. Structure analysis and PAH substrate docking simulations of the Pdo substrate-binding pocket rationalized the experimentally observed metabolic versatility on a molecular scale. Using information obtained in this study and from previous work, we constructed an RHO-centric functional map, allowing pleiotropic and epistatic enzymatic explanation of PAH metabolism. Taking the findings together, the Pdo system is an RHO system with the pleiotropic responsibility of LMW PAH-centric hydroxylation, and its epistatic functional contribution is also crucial for the metabolic quality and quantity of the PAH-MN. PMID:25070740

  4. A topologically driven glass in ring polymers.

    PubMed

    Michieletto, Davide; Turner, Matthew S

    2016-05-10

    The static and dynamic properties of ring polymers in concentrated solutions remains one of the last deep unsolved questions in polymer physics. At the same time, the nature of the glass transition in polymeric systems is also not well understood. In this work, we study a novel glass transition in systems made of circular polymers by exploiting the topological constraints that are conjectured to populate concentrated solutions of rings. We show that such rings strongly interpenetrate through one another, generating an extensive network of topological interactions that dramatically affects their dynamics. We show that a kinetically arrested state can be induced by randomly pinning a small fraction of the rings. This occurs well above the classical glass transition temperature at which microscopic mobility is lost. Our work both demonstrates the existence of long-lived inter-ring penetrations and realizes a novel, topologically induced, glass transition. PMID:27118847

  5. A topologically driven glass in ring polymers

    NASA Astrophysics Data System (ADS)

    Michieletto, Davide

    2016-05-01

    The static and dynamic properties of ring polymers in concentrated solutions remains one of the last deep unsolved questions in polymer physics. At the same time, the nature of the glass transition in polymeric systems is also not well understood. In this work, we study a novel glass transition in systems made of circular polymers by exploiting the topological constraints that are conjectured to populate concentrated solutions of rings. We show that such rings strongly interpenetrate through one another, generating an extensive network of topological interactions that dramatically affects their dynamics. We show that a kinetically arrested state can be induced by randomly pinning a small fraction of the rings. This occurs well above the classical glass transition temperature at which microscopic mobility is lost. Our work both demonstrates the existence of long-lived inter-ring penetrations and realizes a novel, topologically induced, glass transition.

  6. Radioactive gold ring dermatitis

    SciTech Connect

    Miller, R.A.; Aldrich, J.E. )

    1990-08-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.

  7. Variation of particle size distribution in Saturn's rings and search for density waves in Uranus rings

    SciTech Connect

    Yanamandra-Fisher, P.A.

    1988-01-01

    A bimodal size distribution for particles in Saturn's rings has been determined via an analysis of PPS, UVS and RSS occultation data. The variation of the size distribution in featureless regions indicates that the dust variation is nearly constant in the Saturn's rings and exhibits a slight anti-correlation with 1 cm sized particles. Sub-centimeter sized particles increase outward in the rings, with a maximum in the B ring, similar to the variation of 1 cm sized particles. However, the ratio of subcentimeter sized particles to 1 cm sized particles does not vary significantly in the rings. Janus 5:4 density wave differs significantly from the featureless regions. The amount of dust is greater by a factor of about 2. Both dust and sub-centimeter sized particles are strongly anti-correlated with 1 cm sized particles. Partial formation of gaps is evident for both sub- and supra-centimeter sized particles, consistent with the predictions of Goldreich and Tremaine (1978). Dust is insensitive to the gravitational torque associated with the resonance. The results are also consistent with Dones (1987). In wave regions, large particles collide and produce dust and do not break up into smaller particles. The author searched the Uranian rings, via time series analysis methods, to identify periodic phenomena in the rings. A possible wave-like feature has been identified in both the {epsilon} and the {delta} rings of Uranus. A density wave has been identified in the inner half of the {delta} ring. It implies the existence of a moonlet between the {gamma} and {delta} rings and a possible shepherd for the outer edge of the {gamma} ring and an inner shepherd for the {delta} ring. Comparison of density waves in the two ring systems are similar, indicating the similarity of the local ring environments.

  8. Functionalization and kinetic stabilization of the [4]paracyclophane system and aromaticity of its extremely bent benzene ring.

    PubMed

    Tsuji, Takashi; Okuyama, Masahiro; Ohkita, Masakazu; Kawai, Hidetoshi; Suzuki, Takanori

    2003-01-29

    Kinetic stabilization of the [4]paracyclophane skeleton by the introduction of substituents, which serve to sterically hinder reactions at the reactive bridgehead sites, and properties of the resultant [4]paracyclophanes are investigated in this study. Modification of the property of [4]paracyclophane by functionalization is also intended. [4]Paracyclophanes are designed to be derived from the corresponding Dewar benzene isomers via their photochemical aromatization, and the requisite 1,4-bridged Dewar benzenes bearing sterically demanding functional groups are prepared. Irradiation of these precursors under matrix isolation at 77 K leads to the formation of [4]paracyclophanes, which exhibit characteristic electronic absorption spectra. The half-lives of the generated species vary widely from less than 1 min at -90 degrees C to 0.5 h at -20 degrees C, depending on the type of substituents and the pattern of substitution. One of the derivatives, 24, is stable enough and its content in the irradiated mixture is high enough to permit the measurement of the (1)H NMR spectrum. The recorded spectrum, which is reproduced very well by theoretical calculations using the GIAO method at the hybrid HF-DFT (B3LYP/6-31+G*) level, suggests the sustenance of rather strong diatropicity in its severely bent benzene moiety. Calculations on the bent benzene whose geometry is constrained to that calculated for 24 support that aromaticity is retained to a significant extent as compared to that of planar benzene, as judged by the magnetic criteria of aromaticity, that is, diamagnetic susceptibility exaltation and nucleus-independent chemical shift. The reason for the retention of aromaticity despite the severe bending of the benzene ring is discussed. Cyclophane 24 is so strained that it exceeds the corresponding Dewar benzene precursor in energy and thermally reverts to the latter with a half-life of 15 +/- 5 min at -20 degrees C (DeltaG++ = 18.3 +/- 0.3 kcal mol(-1)). PMID:12537493

  9. Integrated semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Jezierski, A. F.; Laybourn, P. J. R.

    1988-02-01

    Ring-waveguide and pill-box structures down to 12 microns in diameter, made in GaAs/GaAlAs heterostructure material, have been designed with output stripe waveguides coupled to the rings via Y-junctions. The waveguides were defined by reactive ion etching, although the inner boundaries of some of the ring waveguides relied on stress and carrier confinement. Lasing has been observed with pulsed drive current, and has been shown to correspond to resonances in the rings, although other resonances have been observed in some of the structures. This type of structure is suitable for use as a light source in monolithic integrated optics.

  10. Viscosity in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.; Shu, F. H.; Cuzzi, J. N.

    1982-01-01

    The technique of estimating the viscosity in Saturn's rings from the damping rate of waves observed to be propagating within the rings is discussed. The wavetrains of attempts using spiral density waves as a diagnostic suffer significant complications that compromise the interpretations. A method that considers the damping of spiral bending waves was used to deduce a kinematic viscosity of 260 (+150, -100) sqcm/sec for the middle of the A ring where bending waves are excited by the 5:3 vertical resonance with Mimas. This value implies upper limits on the particle velocity dispersion and local ring thickness of 0.4 cm/sec and 30 m, respectively.

  11. Saturn's Rings: Pre-Cassini Status and Mission Goals

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Colwell, J. E.; Esposito, L. W.; Porco, C. C.; Murray, C. D.; Nicholson, P. D.; Spilker, L.; Marouf, E. A.; French, R. C.; Rappaport, N.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Theoretical and observational progress in studies of Saturn's ring system since the mid-1980s is reviewed, focussing on advances in configuration and dynamics, composition and size distribution, dust and meteoroids, interactions of the rings with the planet and the magnetosphere, and relationships between the rings and various satellites. The Cassini instrument suite of greatest relevance to ring studies is also summarized, emphasizing how the individual instruments might work together to solve outstanding problems. The Cassini tour is described from the standpoint of ring studies, and major ring science goals are summarized.

  12. Photochemistry of 1,4-Dihydropyridine Derivatives: Diradical Formation, Delocalization and Trapping as a Route to Novel Tricyclic and Tetracyclic Nitrogen Heterocyclic Ring Systems.

    PubMed

    Al-Jalal, Nader A; Ibrahim, Yehia A; Al-Awadi, Nouria A; Ibrahim, Maher R; Sayed, Osama M

    2016-01-01

    Irradiation of an acetonitrile solution of 4-aryl-3,5-dibenzoyl-1,4-dihydropyridine derivatives 1a-c and maleimides 2a-c using medium pressure Hg-arc lamp (λ > 290) nm afforded three different cycloadducts 4, 5, 6 in addition to the oxidation products 3. These results indicate that compounds 1a-c undergoes intermolecular cycloaddition reaction through three biradical intermediates and behave photochemically different than those reported previously for the analogous 3,5-diacetyl and 3,5-dicarboxylic acid derivatives. The present work also offers simple access to novel tricyclic and tetracyclic nitrogen heterocyclic ring systems of potential biological and synthetic applications. The structure of the photoproducts was established spectroscopically and by single crystal X-ray crystallography. PMID:27376257

  13. Technique distribuee de gestion de la charge sur le reseau electrique et ring-tree: Un nouveau systeme de communication P2P

    NASA Astrophysics Data System (ADS)

    Ayoub, Simon

    Le reseau de distribution et de transport de l'electricite se modernise dans plusieurs pays dont le Canada. La nouvelle generation de ce reseau que l'on appelle smart grid, permet entre autre l'automatisation de la production, de la distribution et de la gestion de la charge chez les clients. D'un autre cote, des appareils domestiques intelligents munis d'une interface de communication pour des applications du smart grid commencent a apparaitre sur le marche. Ces appareils intelligents pourraient creer une communaute virtuelle pour optimiser leurs consommations d'une facon distribuee. La gestion distribuee de ces charges intelligentes necessite la communication entre un grand nombre d'equipements electriques. Ceci represente un defi important a relever surtout si on ne veut pas augmenter le cout de l'infrastructure et de la maintenance. Lors de cette these deux systemes distincts ont ete concus : un systeme de communication peer-to-peer, appele Ring-Tree, permettant la communication entre un nombre important de noeuds (jusqu'a de l'ordre de grandeur du million) tel que des appareils electriques communicants et une technique distribuee de gestion de la charge sur le reseau electrique. Le systeme de communication Ring-Tree inclut une nouvelle topologie reseau qui n'a jamais ete definie ou exploitee auparavant. Il inclut egalement des algorithmes pour la creation, l'exploitation et la maintenance de ce reseau. Il est suffisamment simple pour etre mis en oeuvre sur des controleurs associes aux dispositifs tels que des chauffe-eaux, chauffage a accumulation, bornes de recharges electriques, etc. Il n'utilise pas un serveur centralise (ou tres peu, seulement lorsqu'un noeud veut rejoindre le reseau). Il offre une solution distribuee qui peut etre mise en oeuvre sans deploiement d'une infrastructure autre que les controleurs sur les dispositifs vises. Finalement, un temps de reponse de quelques secondes pour atteindre 1'ensemble du reseau peut etre obtenu, ce qui est

  14. Stereoselective synthesis of cis- and trans-2,3-disubstituted tetrahydrofurans via oxonium-prins cyclization: access to the cordigol ring system.

    PubMed

    Spivey, Alan C; Laraia, Luca; Bayly, Andrew R; Rzepa, Henry S; White, Andrew J P

    2010-03-01

    SnBr(4)-promoted oxonium-Prins cyclizations to form 2,3-disubstituted tetrahydrofurans (THFs) are reported. In the absence of an internal nucleophile, the carbocation intermediates are trapped by bromide to give 2,3-cis- and 2,3-trans-configured products; two variations with intramolecular trapping are also reported. One of these allows a single-step stereocontrolled synthesis of the core 2,3-cis-THF ring system of cordigol, a fungicidal polyphenol from the stem bark of Cordia goetzei. For this latter transformation, a stepwise oxonium-Prins/cation trapping pathway rather than orthoquinonemethide formation/hetero-Diels-Alder cycloaddition is supported computationally. PMID:20143863

  15. Edge-on View of Saturn's Rings

    NASA Technical Reports Server (NTRS)

    1996-01-01

    TOP - This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on.

    In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane.

    BOTTOM - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys.

    Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn.

    The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  16. Electro-optical hybrid slip ring

    NASA Astrophysics Data System (ADS)

    Hong, En

    2005-11-01

    The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

  17. The origin and evolution of the Uranian dust rings

    SciTech Connect

    Colwell, J.E.

    1989-01-01

    The numerous dust bands discovered by Voyager 2 at Uranus have lifetimes on the order of 100 years against orbital decay by exospheric drag. A system of low optical depth rings of 10 meter to 1 km sized bodies (moonlet belts) are proposed as continuing sources of the dust particles. The ring system is modeled as a Markov Chain consisting of states through which dust particle evolve with time. Physical processes included in the model are orbit decay by exospheric drag and Poynting-Robertson light drag; destruction of grains by meteoroid impact; transport of dust through the classical rings and moonlet belts; creation of dust particles from meteoroid impacts onto rings, moons, and moonlet belts; liberation of regolith material through ring and moonlet belt particle collisions; and sweepup of ejecta by ring and moonlet belt particles. The optical depth profiles for the main rings from Voyager 2 Photopolarimeter Subsystem (PPS) occultation observation are used in modeling the transport of dust through the rings. Simulations of the Uranus ring system show that this model reproduces the observed characteristics of the Uranus dust rings. The moonlet belt model is applied to the rings of Jupiter, Saturn, and Neptune, and is capable of reproducing some of the observed characteristics of those ring systems. The moonlet belt objects fit on a collisionally derived power-law size distribution with the other components of the ring moon systems. Since the rings and moonlet belts have lifetimes due to viscous spreading less than the age of the solar system, a net model of planetary rings emerges in which the rings are continually created from the disruption of small satellites by meteoroid bombardment.

  18. Ring Buffered Network Bus

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in development at the University of Toledo under a grant from the Glenn Research Center. The objective of this task was to examine the application of the RBNB technologies as a key component in the data sharing, health monitoring and system wide modeling elements of the NASA Aviation Safety Program (AVSP) [Golding, 1997]. System-wide monitoring and modeling of aircraft and air safety systems will require access to all data sources which are relative factors when monitoring or modeling the national airspace such as radar, weather, aircraft performance, engine performance, schedule and planning, airport configuration, flight operations, etc. The data sharing portion of the overall AVSP program is responsible for providing the hardware and software architecture to access and distribute data, including real-time flight operations data, among all of the AVSP elements. The integration of an engine code capable of numerically "flying" through recorded flight paths and weather data using a software tool that allows for distributed access of data to this engine code demonstrates initial steps toward building a system capable of monitoring and modeling the National Airspace.

  19. Ring Around a Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary 'polar-ring' galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. The bright bluish clumps, which are especially prominent in the outer parts of the ring, are regions containing luminous young stars, examples of stellar rebirth from the remnants of an ancient galactic disaster. The polar ring appears to be highly distorted. No regular spiral pattern stands out in the main part of the ring, and the presence of young stars below the main ring on one side and above on the other shows that the ring is warped and does not lie in one plane. Determining the typical ages of the stars in the polar ring is an initial goal of our Polar Ring Science Team that can provide a clue to the evolution of this unusual galaxy. The HST exposures were acquired by the Hubble Heritage Team, consisting of Keith Noll, Howard Bond, Carol Christian, Jayanne English, Lisa Frattare, Forrest Hamilton, Anne Kinney and Zolt Levay, and guest collaborators Jay Gallagher (University of Wisconsin-Madison), Lynn Matthews (National Radio Astronomy Observatory-Charlottesville), and Linda Sparke (University of Wisconsin-Madison).

  20. Hydrothermal alteration in the Valles caldera ring fracture zone and core hole VC-1: evidence for multiple hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Woldegabriel, Giday

    1990-02-01

    Two types of hydrothermal mineral assemblages, kaolinite-alunite and sericite-chlorite were recognized in outcrop and core samples from the Jemez volcanic field, New Mexico. Active and fossil acid-sulfate hydrothermal activity, producing kaolinite-alunite alteration occurs along the caldera ring fracture and within the resurgent dome, whereas alterations of the chlorite-sericite type are mostly confined to subsurface rocks. K/Ar dates on illitic clays (<2 μm, 2-0.25 μm and <0.25 μm) separated from hydrothermally altered samples are used to document hydrothermal episodes in pre-caldera rocks of the Jemez volcanic field. The clay separates are illitic (75-95% illite layers) with K 2O contents of 8.24-8.95% in the core samples and 4.22-6.67% in the outcrops. Three episodes of hydrothermal alteration are now recognized in the Jemez Mountains region based on K/Ar age dates of illites. The earliest event (≤17-11 Ma, n=4) occurred within altered and illite-rich (≥90% illite layers) lowermost Paleozoic rocks in core hole VC-1 and may correlate with the inception of volcanism in the Jemez region (≤16.5 Ma). Illitic clays from altered andesite and rhyolite from the topographic rim of the Valles caldera were dated at 8.2 and 6.96 Ma, suggesting that a hydrothermal event related to the waning stages of the Keres Group volcanism (13-5.8 Ma) was responsible for the alteration. These dates overlap minimum ages obtained on slightly altered basalt (8.05 Ma) and andesite lava (7.07 Ma) from the southern and northwestern topographic rim of the Valles caldera, respectively. Ages of 1.21 and 1.34 Ma from illite-rich (≥90% illite layers), hydrothermally altered Paleozoic sandstone at a depth of 479 m in VC-1 suggest hydrothermal activity contemporaneous with the formation of the Toledo (1.45 Ma) and Valles (1.12 Ma) calderas. Ore minerals of sphalerite, chalcopyrite, galena, barite, and molybdenite mineralization occur in the lower half of VC-1 and are related to the Toledo

  1. Design of a loop resonator with a split-ring-resonator (SRR) for a human-body coil in 3 T MRI systems

    NASA Astrophysics Data System (ADS)

    Son, Hyeok Woo; Cho, Young Ki; Kim, Byung Mun; Back, Hyun Man; Yoo, Hyoungsuk

    2016-04-01

    A new radio-frequency (RF) resonator for Nuclear Magnetic Resonance (NMR) imaging at clinical magnetic resonance imaging (MRI) systems is proposed in this paper. An approach based on the effects of the properties of metamaterials in split-ring resonators (SRRs) is used to design a new loop resonator with a SRR for NMR imaging. This loop resonator with a SRR is designed for NMR imaging at 3 T MRI systems. The 3D electromagnetic simulation was used to optimize the design of the proposed RF resonator and analyze it's performance at 3 T MRI systems. The proposed RF resonator provides strong penetrating magnetic fields at the center of the human phantom model, approximately 10%, as compared to the traditional loop-type RF resonator used for NMR imaging at clinical MRI systems. We also designed an 8-channel body coil for human-body NMR imaging by using the proposed loop resonator with a SRR. This body coil also produces more homogeneous and highly penetrating magnetic fields into the human phantom model.

  2. Smoke Ring Physics

    ERIC Educational Resources Information Center

    Huggins, Elisha

    2011-01-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampere's law in an introductory physics course. We discuss these common features. (Contains 7 figures.)

  3. Illustration of Saturn's Rings

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This illustration shows a close-up of Saturn's rings. These rings are thought to have formed from material that was unable to form into a Moon because of tidal forces from Saturn, or from a Moon that was broken up by Saturn's tidal forces.

  4. Lower esophageal ring (Schatzki)

    MedlinePlus

    ... narrowed area to stretch the ring. Sometimes, a balloon is placed in the area and inflated, to help widen the ring. Outlook (Prognosis) Swallowing problems may return. You may need repeat treatment. When to Contact a Medical Professional Call your health care provider if you ...

  5. EBT ring physics

    SciTech Connect

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers. (MOW)

  6. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  7. The Fermilab recycler ring

    SciTech Connect

    Martin Hu

    2001-07-24

    The Fermilab Recycler is a permanent magnet storage ring for the accumulation of antiprotons from the Antiproton Source, and the recovery and cooling of the antiprotons remaining at the end of a Tevatron store. It is an integral part of the Fermilab III luminosity upgrade. The following paper describes the design features, operational and commissioning status of the Recycler Ring.

  8. Telemetry carrier ring and support

    NASA Technical Reports Server (NTRS)

    Wakeman, Thomas G. (Inventor)

    1992-01-01

    A telemetry carrier ring for use in a gas turbine engine includes an annular support ring connected to the engine and an annular carrier ring coupled to the support ring, each ring exhibiting different growth characteristics in response to thermal and mechanical loading. The carrier ring is coupled to the support ring by a plurality of circumferentially spaced web members which are relatively thin in an engine radial direction to provide a predetermined degree of radial flexibility. the web members have a circumferential width and straight axial line of action selected to transfer torque and thrust between the support ring and the carrier ring without substantial deflection. The use of the web members with radial flexibility provides compensation between the support ring and the carrier ring since the carrier ring grows at a different rate than the supporting ring.

  9. An evolving view of Saturn's dynamic rings.

    PubMed

    Cuzzi, J N; Burns, J A; Charnoz, S; Clark, R N; Colwell, J E; Dones, L; Esposito, L W; Filacchione, G; French, R G; Hedman, M M; Kempf, S; Marouf, E A; Murray, C D; Nicholson, P D; Porco, C C; Schmidt, J; Showalter, M R; Spilker, L J; Spitale, J N; Srama, R; Sremcević, M; Tiscareno, M S; Weiss, J

    2010-03-19

    We review our understanding of Saturn's rings after nearly 6 years of observations by the Cassini spacecraft. Saturn's rings are composed mostly of water ice but also contain an undetermined reddish contaminant. The rings exhibit a range of structure across many spatial scales; some of this involves the interplay of the fluid nature and the self-gravity of innumerable orbiting centimeter- to meter-sized particles, and the effects of several peripheral and embedded moonlets, but much remains unexplained. A few aspects of ring structure change on time scales as short as days. It remains unclear whether the vigorous evolutionary processes to which the rings are subject imply a much younger age than that of the solar system. Processes on view at Saturn have parallels in circumstellar disks. PMID:20299586

  10. Saturn ring particles as dynamic ephemeral bodies.

    PubMed

    Davis, D R; Weidenschilling, S J; Chapman, C R; Greenberg, R

    1984-05-18

    Although Saturn's rings are within the Roche zone, the accretion of centimeter-sized particles into large aggregates many meters in diameter occurs readily, on a time scale of weeks. These aggregates are disrupted when tidal stresses exceed their very low strengths; thus most of the mass of the ring system is continually processed through a population of large "dynamic ephemeral bodies," which are continually forming and disintegrating. These large aggregates are not at all like the idealized ice spheres often used in modeling Saturn's ring dynamics. Their coefficient of restitution is low, hence they form a monolayer in the ring plane. The optically observable characteristics of the rings are dominated by the swarm of centimeter-sized particles. PMID:17780622

  11. The Arp Ring: Galactic or extragalactic?

    NASA Technical Reports Server (NTRS)

    Abolins, J. A.; Rice, W. L.

    1987-01-01

    The Arp Ring is a faint, loop-like structure around the northern end of M81 which becomes apparent only on deep optical photographs of the galaxy. The nature of the Ring and its proximity to M81 are uncertain. Is it simply foreground structure, part of this galaxy, or is it within the M81 system? Infrared Astronomy Satellite (IRAS) maps of the region show a far-infrared counterpart of the Ring. The infrared data are compared with previous optical and radio observations to try to ascertain its physical nature. The poor correlation found between the common infrared/optical structure and the distribution of extragalactic neutral hydrogen, and the fact that its infrared properties are indistinguishable from those of nearby galactic cirrus, imply that the Arp Ring is simply a ring structure in the galactic cirrus.

  12. Jupiter's Rings: Sharpest View

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons spacecraft took the best images of Jupiter's charcoal-black rings as it approached and then looked back at Jupiter. The top image was taken on approach, showing three well-defined lanes of gravel- to boulder-sized material composing the bulk of the rings, as well as lesser amounts of material between the rings. New Horizons snapped the lower image after it had passed Jupiter on February 28, 2007, and looked back in a direction toward the sun. The image is sharply focused, though it appears fuzzy due to the cloud of dust-sized particles enveloping the rings. The dust is brightly illuminated in the same way the dust on a dirty windshield lights up when you drive toward a 'low' sun. The narrow rings are confined in their orbits by small 'shepherding' moons.

  13. Structural modeling of the flagellum MS ring protein FliF reveals similarities to the type III secretion system and sporulation complex

    PubMed Central

    2016-01-01

    The flagellum is a large proteinaceous organelle found at the surface of many bacteria, whose primary role is to allow motility through the rotation of a long extracellular filament. It is an essential virulence factor in many pathogenic species, and is also a priming component in the formation of antibiotic-resistant biofilms. The flagellum consists of the export apparatus on the cytosolic side; the basal body and rotor, spanning the bacterial membrane(s) and periplasm; and the hook-filament, that protrudes away from the bacterial surface. Formation of the basal body MS ring region, constituted of multiple copies of the protein FliF, is one of the initial steps of flagellum assembly. However, the precise architecture of FliF is poorly understood. Here, I report a bioinformatics analysis of the FliF sequence from various bacterial species, suggesting that its periplasmic region is composed of three globular domains. The first two are homologous to that of the type III secretion system injectisome proteins SctJ, and the third possesses a similar fold to that of the sporulation complex component SpoIIIAG. I also describe that Chlamydia possesses an unusual FliF protein, lacking part of the SctJ homology domain and the SpoIIIAG-like domain, and fused to the rotor component FliG at its C-terminus. Finally, I have combined the sequence analysis of FliF with the EM map of the MS ring, to propose the first atomic model for the FliF oligomer, suggesting that FliF is structurally akin to a fusion of the two injectisome components SctJ and SctD. These results further define the relationship between the flagellum, injectisome and sporulation complex, and will facilitate future structural characterization of the flagellum basal body. PMID:26925337

  14. STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED BY ARCHITECTURAL FINISH. TENSION RING ROLLER SUPPORT AT COLUMN OBSCURED BY COLUMN COVERINGS. - Houston Astrodome, 8400 Kirby Drive, Houston, Harris County, TX

  15. Constraining Particle Sizes of Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Becker, T. M.; Colwell, J.; Esposito, L. W.

    2011-12-01

    Saturn's beauty is often attributed to the magnificent rings that encircle the planet. Although admired for hundreds of years, we are now just beginning to understand the complexity of the rings as a result of new data from the Cassini orbiter. Studying occultations of the rings provides information about the distribution and sizes of the particles that define the rings. During one solar occultation, the Ultraviolet Imaging Spectrograph (UVIS) on board Cassini was slightly misaligned with the Sun, decreasing the amount of direct solar signal to ~1% of the normal value. As a result, UVIS detected a peak in photon counts above the non-occulted signal due to forward-scattered light diffracted by the small particles in the F Ring. There is a direct relationship between the size of the particles and the intensity of the light scattered. We utilize this relationship in a model that replicates the misalignment and calculates the amount of light that would be detected as a function of the particle sizes in the ring. We present new results from the model that constrain the size distribution of the dynamically active F Ring, contributing to the study of the origin and evolution of Saturn's ring system.

  16. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  17. Thermal and dynamic analysis of the RING (Radiatively-cooled, Inertially-driven Nuclear Generator) power system radiator

    SciTech Connect

    Apley, W.J.; Babb, A.L.

    1989-01-01

    The nuclear option for a space-based power system appears most suitable for missions that require long-term, sustained operation at power levels above 100 kWe. Systems currently available operate at relatively low thermal efficiencies (6--10%). Thus, a 100 kWe system must discharge nearly 2 MWth of waste heat through the comparatively inefficient process of radiative cooling. The impact of the resultant radiator assembly size on overall power system weight is significant, and has led to proposals for radiators with potentially higher efficiencies. Examples include the: liquid droplet radiator; fabric radiator; bubble membrane radiator; rotating film radiator; and dust radiator. 14 refs., 2 figs., 2 tabs.

  18. The postman always rings twice: two cases of shotgun deaths associated with an unconventional home security alarm system.

    PubMed

    Asirdizer, Mahmut; Turkmen, Nursel; Akan, Okan; Yavuz, Mehmet Sunay

    2014-06-01

    Injury and death cases caused by booby traps are not common in forensic medicine practice. Besides, installation of booby traps including firearms is generally for suicidal and rarely for homicidal purposes. Although few patents were described about home security alarm system that were created by firearms in the United States, 1 sample of injury with a similar unconventional mechanism of home safety system was reported by Asirdizer and Yavuz in 2009. In the published case report, the story of an electrical technician who was invited to a summer house by the homeowner to check the home security alarm system was reported. In the so-called report, he was stated to be injured by the shotgun attached to the unconventional home security alarm system while checking the system. As a result, the homeowner was convicted of a possible intent to cause a life-threatening injury to the technician.The so-called homeowner and his wife died by the same shotgun attached to the same unconventional home security alarm system 4 years on from the first event. In the present case report, we have aimed to present the findings of the crime scene and the autopsies of these unusual 2 deaths and to discuss individual and legal factors in paving the way for the deaths of 2 people. PMID:24781392

  19. Behavioral Mapless Navigation Using Rings

    NASA Technical Reports Server (NTRS)

    Monroe, Randall P.; Miller, Samuel A.; Bradley, Arthur T.

    2012-01-01

    This paper presents work on the development and implementation of a novel approach to robotic navigation. In this system, map-building and localization for obstacle avoidance are discarded in favor of moment-by-moment behavioral processing of the sonar sensor data. To accomplish this, we developed a network of behaviors that communicate through the passing of rings, data structures that are similar in form to the sonar data itself and express the decisions of each behavior. Through the use of these rings, behaviors can moderate each other, conflicting impulses can be mediated, and designers can easily connect modules to create complex emergent navigational techniques. We discuss the development of a number of these modules and their successful use as a navigation system in the Trinity omnidirectional robot.

  20. Seal ring installation tool

    NASA Technical Reports Server (NTRS)

    Haselmaier, L. Haynes (Inventor)

    2004-01-01

    A seal ring tool that allows an installer to position a primary seal ring between hub ends of pipe flanges that are being assembled together. The tool includes a pivoting handle member and extension arms attached to the pivoting handle member. The ends of the arms have side indentation type longitudinal grooves angled toward one another for holding the primary seal ring in place between the hubs of respective pipes that are to be attached together. The arms of the tool can also have flat sides that can be used to abut against an optional second larger seal that is supported within a groove in one of the hub ends so that the second hub end can then be moved against the other side of the primary seal ring. Once the seal ring is positioned between the pipe hubs, the pipe hubs can be moved about the seal ring due to the flat sides of the arms of the tool. The tool eliminates the chances of damaging and contaminating seal rings being installed within pipe hubs that are being attached to one another.

  1. Hot piston ring tests

    NASA Technical Reports Server (NTRS)

    Allen, David J.; Tomazic, William A.

    1987-01-01

    As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

  2. Saturn's Ring: Pre-Cassini Status and Mission Goals

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeff N.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    In November 1980, and again in August 1981, identical Voyager spacecraft flew through the Saturn system, changing forever the way we think about planetary rings. Although Saturn's rings had been the only known ring system for three centuries, a ring system around Uranus had been discovered by stellar occultations from Earth in 1977, and the nearly transparent ring of Jupiter was imaged by Voyager in 1979 (the presence of material there had been inferred from charged particle experiments on Pioneer 10 and 11 several years earlier). While Saturn had thus temporarily lost its uniqueness as having the only ring system, with Voyager it handily recaptured the role of having the most fascinating one. The Voyager breakthroughs included spiral density and bending waves such as cause galactic structure; ubiquitous fine-scale radial 'irregular' structure, with the appearance of record-grooves; regional and local variations in particle color; complex, azimuthally variable ring structure; empty gaps in the rings, some containing very regular, sharp-edged, elliptical rings and one containing both a small moonlet and incomplete arcs of dusty material; and shadowy 'spokes' that flicker across the main rings. One of the paradigm shifts of this period was the realization that many aspects of planetary rings, and even the ring systems themselves, could be 'recent' on geological timescales. These early results are reviewed and summarized in the Arizona Space Science series volumes 'Saturn'. (An excellent review of ring dynamics at a formative stage is by Goldreich and Tremaine.) From the mid 1980's to the time of this writing, progress has been steady, while at a less heady pace, and some of the novel ring properties revealed by Voyager 1 and 2 are beginning to be better understood. It is clearly impossible to cite, much less review, every advance over the last decade; however, below we summarize the main advances in understanding of Saturn's rings since the mid 1980's, in the context

  3. Acne vulgarism treatment using ultra-short laser pulse generated by micro- and nano-ring resonator system.

    PubMed

    Jalil, M A; Phelawan, J; Aziz, M S; Saktioto, T; Ong, C T; Yupapin, Preecha P

    2013-04-01

    Acne vulgaris is adebilitating dermatologic disease, and is conventionally treated by laser therapy using a microring resonator system. An evolving understanding of laser-tissue interactions involving Propioni bacterium acneproducing porphyrins, and the development of lasers to target the sebaceous glands, has led to the development of an escalating number of laser light for acne treatment. The results show that the full width at half maximum of the proposed laser pulse of 0.15 nm can be generated using a microring resonator system. The power of the laser is 200 W and the wavelength laser is 1,032 nm, which is proposed as a treatment of acne vulgaris diseases. PMID:22991968

  4. Dynamics of the Uranian Rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    Some of the problems of the shepherding satellite model of Goldreich ant tremaine are discussed. The following topics are studied: (1) optical depths of the all the observed narrow rings; (2) satellite and ring separation timescales; (3) ring edge sharpness; (4) shock formation in narrow rings; (5) the existence of small satellites near the Uranian rings; and (6) the apse and node alignments of the eccentric and inclined rings.

  5. CASSINI UVIS STELLAR OCCULTATION OBSERVATIONS OF SATURN's RINGS

    SciTech Connect

    Colwell, J. E.; Jerousek, R. G.; Pettis, D.; Bradley, E. T.; Esposito, L. W.; Sremcevic, M.

    2010-12-15

    The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high-speed photometer (HSP) that has observed more than 100 stellar occultations by Saturn's rings. Here, we document a standardized technique applied to the UVIS-HSP ring occultation datasets delivered to the Planetary Data System as higher level data products. These observations provide measurements of ring structure that approaches the scale of the largest common ring particles ({approx}5 m). The combination of multiple occultations at different viewing geometries enables reconstruction of the three-dimensional structure of the rings. This inversion of the occultation data depends on accurate calibration of the data so that occultations of different stars taken at different times and under different viewing conditions can be combined to retrieve ring structure. We provide examples of the structure of the rings as seen from several occultations at different incidence angles to the rings, illustrating changes in the apparent structure with viewing geometry.

  6. The vertical structure and thickness of Saturn's rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, J. N.; Burns, J. A.; Durisen, R. H.; Hamill, P. M.

    1979-01-01

    An explanation for the vertical structure and thickness of Saturn's rings compatible with observational data is presented. The model of the rings as being many particles thick is shown to be possible, with random particle motions preventing the complete flattening of the system and a gaussian distribution of particle density with vertical displacement. The model prediction of a maximum ring thickness of tens of meters, however, is in conflict with observations of ring thickness of at least 0.8 km at ring-plane passage. It is shown that perturbations to ring particle orbits caused by the sun and Saturn's large satellites may produce long- and short-period coherent vertical ring displacements and a nonlinear displacement of the ring plane from the equatorial plane with radial distance, leading to an apparent edge-on thickness of a few hundred meters.

  7. Theodolite Ring Lights

    NASA Technical Reports Server (NTRS)

    Clark, David

    2006-01-01

    Theodolite ring lights have been invented to ease a difficulty encountered in the well-established optical-metrology practice of using highly reflective spherical tooling balls as position references. A theodolite ring light produces a more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very bright light source that is well centered on the optical axis of the instrument. It can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter.

  8. Dynamics of planetary rings

    NASA Astrophysics Data System (ADS)

    Araki, S.

    1991-02-01

    The modeling of the dynamics of particle collisions within planetary rings is discussed. Particles in the rings collide with one another because they have small random motions in addition to their orbital velocity. The orbital speed is roughly 10 km/s, while the random motions have an average speed of about a tenth of a millimeter per second. As a result, the particle collisions are very gentle. Numerical analysis and simulation of the ring dynamics, performed with the aid of a supercomputer, is outlined.

  9. Alternative parallel ring protocols

    NASA Technical Reports Server (NTRS)

    Mukkamala, R.; Foudriat, E. C.; Maly, Kurt J.; Kale, V.

    1990-01-01

    Communication protocols are know to influence the utilization and performance of communication network. The effect of two token ring protocols on a gigabit network with multiple ring structure is investigated. In the first protocol, a mode sends at most one message on receiving a token. In the second protocol, a mode sends all the waiting messages when a token is received. The behavior of these protocols is shown to be highly dependent on the number of rings as well as the load in the network.

  10. Biosynthesis of vitamin B12: nature of the volatile fragment generated during formation of the corrin ring system.

    PubMed Central

    Mombelli, L; Nussbaumer, C; Weber, H; Müller, G; Arigoni, D

    1981-01-01

    It is shown with the help of radiolabeled substrates that biological formation of the corrin ligand system of cobyrinic acid is linked with the release of an equivalent of acetic acid from a hydroporphinoid precursor in which the C-20 atom has undergone methylation prior to its excision from the macrocycle. PMID:6938989

  11. Saturn's satellites and rings: Huygens' heritage

    NASA Astrophysics Data System (ADS)

    Ferrari, Cécile

    Three and a half centuries ago, Christiaan Huygens (1629 - 1695) discovered Saturn's largest moon Titan. He also understood that a ring surrounded the planet by studying the variable aspect of Saturn in the sky during its nearly 30-year-long revolution around the Sun. Since that time, generations of astronomers have been pursuing the exploration of the planet's neighbourhood with ever more powerful telescopes and instruments. Most of the regular satellites in the system have been discovered throughout the centuries during the Earth's crossing of Saturn's ring plane, when the rings' bright light turns off. The Voyager 1 and 2 spacecraft completed the picture in the early eighties by discovering the smallest moons, embedded in the ring system. Fifteen years later it has been demonstrated that ground-based telescopes were able to detect the largest particles in Saturn's rings. Massive storage and large CCD arrays have yielded recently the discovery of an important family of irregular satellites around Saturn. More than a complete inventory of the Saturn's satellite system, the quest for satellites yields important clues to the conditions of formation of the whole Saturnian system and to the close relationship between rings and the regular system of satellites.

  12. High-Speed Ring Bus

    NASA Technical Reports Server (NTRS)

    Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

    2010-01-01

    is no centralized arbitration or bus granting. The JPL design provides for autonomous synchronization of the nodes on the ring bus. An address-synchronous latency adjust buffer (LAB) has been designed that cannot get out of synchronization and needs no external input. Also, a priority-driven cable selection behavior has been programmed into each unit on the ring bus. This makes the bus able to connect itself up, according to a maximum redundancy priority system, without the need for computer intervention at startup. Switching around a failed or switched-off unit is also autonomous. The JPL bus provides a map of all the active units for the host computer to read and use for fault management. With regard to timing, this enhanced bus recognizes coordinated timing on a spacecraft as critical and addresses this with a single source of absolute and relative time, which is broadcast to all units on the bus with synchronization maintained to the tens of nanoseconds. Each BIU consists of up to five programmable triggers, which may be programmed for synchronization of events within the spacecraft of instrument. All JPL-formatted data transmitted on the ring bus are automatically time-stamped.

  13. Oscillations and resonances in electrostatically supported dust rings

    SciTech Connect

    Melandsoe, F.; Havnes, O. )

    1991-04-01

    The authors show that planetary dust rings which are electrostatically supported, i.e., the ring thickness is determined by a balance between the component of gravity toward the central plane and the expanding electrostatic force on the dust, will oscillate if the ambient plasma conditions are changed. The oscillation frequency of tenuous clouds is found analytically to be {radical}3 times the local Kepler frequency. This is confirmed by numerical results which also show that the oscillation frequency decreases for denser rings. While a tenuous ring has one oscillation frequency throughout, the different parts of a dense ring, e.g., the central density and ring edge position, oscillate with different frequencies. The oscillations become increasingly complex for denser rings. They have concentrated on tenuous rings and looked for resonances between the oscillation frequency {radical}3 {Omega}{sub K} and other naturally occurring frequencies in a ring system. They have investigated the consequences if magnetospheric corotating plasma is not symmetric in azimuth. This can lead to resonances with the vertical dust profile oscillaitons of orbiting dust rings. They determine the major resonance distances around Jupiter and Saturn and find striking coincidences with features in both ring systems which indicate that such resonances may have effects beyond that of simply uncreasing the thickness of a ring at a resonance distance.

  14. Electronic Properties of Semiconductor Quantum-Ring Structures

    NASA Astrophysics Data System (ADS)

    Pacheco, Mónica; Fuster, Gonzalo; Barticevic, Zdenka

    2002-03-01

    Motivated by the interesting electronic properties exhibited by these nanorings when they are threaded by a magnetic field, we studied a new semiconductor structure formed by two coupled rings which are concentrically disposed. In order to calculate the two-ring electronic spectrum it is assumed that the in-plane electronic-potential of each ring is generated by a rotation, around the ring axis, of a one-dimensional parabolic potential centered to a distance ρ=ρo of the ring center. The potential of the two-rings system is then assumed as a superposition of a potential for each ring with their minimum at different radii and being truncated in the intersection point. In this way a potential barrier is formed in between the rings. We solve the in-plane problem by expanding the corresponding envelope function as a linear combination of solutions of isolated rings. We have made a detailed study about the influence of the characteristic confinement-parameters of each rings, and of the barrier strength, on the electronic energy spectrum of the system. A uniform magnetic field is applied along the common ring axis and we explore the effects on the Aharonov-Bohm-type oscillations in the energy levels caused by the particular geometry of two coupled quantum-rings.

  15. Dipolar bosons on an optical lattice ring

    NASA Astrophysics Data System (ADS)

    Maik, Michał; Buonsante, Pierfrancesco; Vezzani, Alessandro; Zakrzewski, Jakub

    2011-11-01

    We consider an ultrasmall system of polarized bosons on an optical lattice with a ring topology, interacting via long-range dipole-dipole interactions. Dipoles polarized perpendicular to the plane of the ring reveal sharp transitions between different density-wave phases. As the strength of the dipolar interactions is varied, the behavior of the transitions is first-order-like. For dipoles polarized in the plane of the ring, the transitions between possible phases show pronounced sensitivity to the lattice depth. The abundance of possible configurations may be useful for quantum-information applications.

  16. Storage Ring EDM Experiments

    NASA Astrophysics Data System (ADS)

    Semertzidis, Yannis K.

    2016-04-01

    Dedicated storage ring electric dipole moment (EDM) methods show great promise advancing the sensitivity level by a couple orders of magnitude over currently planned hadronic EDM experiments. We describe the present status and recent updates of the field.

  17. Heating Saturn's Clumpy Rings

    NASA Astrophysics Data System (ADS)

    Turner, Neal J.; Morishima, Ryuji; Spilker, Linda J.

    2015-11-01

    We model Cassini CIRS data using a Monte Carlo radiative transfer -- thermal balance technique first developed for protostellar disks, with the goals of:1. Exploring whether the A- and B-ring temperatures' variation with viewing angle is consistent with the wake structures suggested by the observed azimuthal asymmetry in optical depth, by analytic arguments, and by numerical N-body modeling.2. Better constraining the shape, size, spacing and optical depths of substructure in the A-ring, using the unexpectedly high temperatures observed at equinox. If the wake features have high enough contrast, Saturn-shine may penetrate the gaps between the wakes and heat thering particles both top and bottom.3. Determining how much of the heating of the A- and B-rings' unlit sides is due to radiative transport and how much is due to particle motions, especially vertical motions. This will help in constraining the rings' surface densities and masses.

  18. Saturn's dynamic D ring

    USGS Publications Warehouse

    Hedman, M.M.; Burns, J.A.; Showalter, M.R.; Porco, C.C.; Nicholson, P.D.; Bosh, A.S.; Tiscareno, M.S.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Clark, R.

    2007-01-01

    The Cassini spacecraft has provided the first clear images of the D ring since the Voyager missions. These observations show that the structure of the D ring has undergone significant changes over the last 25 years. The brightest of the three ringlets seen in the Voyager images (named D72), has transformed from a narrow, <40-km wide ringlet to a much broader and more diffuse 250-km wide feature. In addition, its center of light has shifted inwards by over 200 km relative to other features in the D ring. Cassini also finds that the locations of other narrow features in the D ring and the structure of the diffuse material in the D ring differ from those measured by Voyager. Furthermore, Cassini has detected additional ringlets and structures in the D ring that were not observed by Voyager. These include a sheet of material just interior to the inner edge of the C ring that is only observable at phase angles below about 60??. New photometric and spectroscopic data from the ISS (Imaging Science Subsystem) and VIMS (Visual and Infrared Mapping Spectrometer) instruments onboard Cassini show the D ring contains a variety of different particle populations with typical particle sizes ranging from 1 to 100 microns. High-resolution images reveal fine-scale structures in the D ring that appear to be variable in time and/or longitude. Particularly interesting is a remarkably regular, periodic structure with a wavelength of ??? 30 ?? km extending between orbital radii of 73,200 and 74,000 km. A similar structure was previously observed in 1995 during the occultation of the star GSC5249-01240, at which time it had a wavelength of ??? 60 ?? km. We interpret this structure as a periodic vertical corrugation in the D ring produced by differential nodal regression of an initially inclined ring. We speculate that this structure may have formed in response to an impact with a comet or meteoroid in early 1984. ?? 2006 Elsevier Inc. All rights reserved.

  19. Stability of equilibrium of a superconducting ring that levitates in the field of a fixed ring with constant current

    NASA Astrophysics Data System (ADS)

    Bishaev, A. M.; Bush, A. A.; Gavrikov, M. B.; Kamentsev, K. E.; Kozintseva, M. V.; Savel'ev, V. V.; Sigov, A. S.

    2015-11-01

    In order to develop a plasma trap with levitating superconducting magnetic coils, it is necessary to search for their stable levitating states. An analytical expression for the potential energy of a single superconducting ring that captures a fixed magnetic flux in the field of a fixed ring with constant current versus the coordinate of the free ring on the axis of the system, deviation angle of its axis from the axis of the system, and radial displacement of its plane is derived for uniform gravity field in the thin ring approximation. The calculated stable levitation states of the superconducting ring in the field of the ring with constant current are proven in experiments. The generalization of such an approach to the levitation of several rings makes it possible to search for stable levitation states of several coils that form a magnetic system of a multipole trap.

  20. Performance of a two-mirror, four-reflection, ring-field optical system at {lambda}=13 nm

    SciTech Connect

    La Fontaine, B.; Gaines, D.P.; Kania, D.R.; Sommargren, G.E.; Baker, S.L.; Ciarlo, D.

    1996-05-24

    Performance of an Extreme Ultraviolet Lithography (EUVL) imaging optic was characterized by printing resolution test images in resist. While features as small as 0.137 {mu}m were successfully printed, a resolution of 0.175 {mu}m better represents the performance of the system over the full 0.9 mm{sup 2} image field. The contrast of the aerial image was estimated to be about 40% or less for the fine features printed. This low contrast value is attributed to a degradation of the modulation transfer function due to presence of scattered light in the image.

  1. Facile Access to Cyclooctanoid Ring Systems via Microwave-Assisted Tandem 6-exo dig Cyclization-Rearrangement Sequence

    PubMed Central

    Feldman, Aaron W.; Ovaska, Sami I.; Ovaska, Timo V.

    2014-01-01

    Appropriately substituted 5-alkyn-1-ol systems bearing a nitrile moiety at the triple bond serve as versatile precursors to a variety of cyclooctenone derivatives via a “one-pot” base-catalyzed oxyanionic 6-exo dig cyclization/Claisen rearrangement sequence under microwave irradiation. It was found that the initially formed cyclic intermediate consists of a mixture of endo and exocyclic isomers, which appear to be in equilibrium under the reaction conditions. However, the only observed products from these reactions are α-cyano substituted cyclooctenones, derived from the exocyclic dihydrofuran intermediates. PMID:24994941

  2. Mosaic of Saturn's rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This detailed mosaic of the underside of the Cassini Division was obtained by Voyager 1 with a resolution of about 10 kilometers. The classical Cassini Division appears here to the right of center as five bright rings with substantial blacks gap on either side. The inner edge of the A Ring, to the left of center, is the brightest part of this image. The fine-scale wave structure in this region has been interpreted as being the result of gravitational density waves.

  3. Saturn's B rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's B Ring and Cassini Division was taken through the Clear filter from a distance of 12.6 million km on 3 November 1980. The Cassini Division separating the A and B Rings is clearly not an empty region. The Division shows several substantial well-defined ringlets. JPL managed the Voyager Project for NASA's Office of Space Science.

  4. Properties of the indole ring in metal complexes. A comparison with the phenol ring.

    PubMed

    Shimazaki, Yuichi; Yajima, Tatsuo; Yamauchi, Osamu

    2015-07-01

    Tryptophan (Trp), an essential amino acid, has an indole ring with a high electron density and is frequently seen at the proximal position of the metal site in metalloproteins. For example, the indole ring of Trp has been reported to interact weakly with Cu(I) in a Cu chaperone CusF. Another aromatic amino acid, tyrosine (Tyr), has a phenol ring, which is an important metal binding site in various metalloproteins. Although the structures of the aromatic rings are different, they both have a weakly acidic moiety and perform some similar roles in biological systems, such as radical formation and electron transfer. In this review, we focus on these and other properties of the indole and phenol rings in metal-containing systems. PMID:25817198

  5. Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

    NASA Astrophysics Data System (ADS)

    Schneider, Glenn

    2014-10-01

    How do circumstellar (CS) disks evolve and form planetary systems? Is our solar system's two-component debris disk (DD) typical? Are planets implicated by evidence of dynamical stirring in disks? Are DD architectures correlated with stellar mass? To address these highly-compelling questions of fundamental astrophysical import, we propose follow-up STIS coronagraphy of five intermediate-inclination ring-like DDs. These images will provide unprecedented clarity, sensitivity, and photometric efficacy to: 1) Study the spatial distribution of dust as close as 0.2" from the host stars enabling us to infer the existence and properties of unseen co-orbiting planets, and to probe disk-planet interactions across stellar ages and spectral types; 2) Provide spatially resolved imaging within DD regions previously unsampled to significantly improve constraints on disk grain properties and radial segregation of grain populations as a function of stellocentric distance (and thus temperature); 3) Produce high-fidelity images of DD substructures for dynamical interpretation, constraining the possibilities for planetary system architectures; 4) Obtain deep images of regions beyond the primary, bright debris features to study small-grain populations that might be unbound from the system and affected by both extrinsic and intrinsic forces and may inform about the level of dynamical activity in the planetesimal belt; 5) Provide, through the HLA, the highest quality and most complete, value-added data products for a seminal legacy data set of spatially resolvable light-scattering DDs, thus enabling multi-wavelength investigations with new and future ground- and space-based facilities.

  6. Localization effects in the Auger spectra of ring nitrogen systems: Pyridine, poly(2-vinyl)pyridine, borazine, and boron nitride

    SciTech Connect

    Rye, R.R.; Kelber, J.A.; Kellogg, G.E.; Nebesny, K.W.; Lichtenberger, D.L.

    1987-04-15

    The N(KVV) Auger spectra of gas phase pyridine (C/sub 5/H/sub 5/N) and borazine (B/sub 3/N/sub 3/H/sub 6/), and of solid phase poly(2-vinyl)pyridine (PVP) and hexagonal boron nitride ((BN)/sub x/) are reported and analyzed. The data indicate two Auger ''fingerprint'' types of nitrogen. Ammonia (NH/sub 3/) is the prototype for the first, where three of the five valence electrons are sigma bonding and the other two are the lone pair. This localized electronic structure gives rise to relatively sharp features in the N(KVV) spectrum. Typical of the second fingerprint type is pyridine, where there are two sigma bonding electrons, a lone pair of electrons, and one electron contributing to the delocalized ..pi.. system. Theoretical nitrogen Auger transition energies and intensities are calculated for pyridine to demonstrate the general origin of the overlapping features in the relatively broad N(KVV) spectrum of this molecule. PVP fits into the second fingerprint type while borazine and boron nitride give nitrogen Auger spectra more like ammonia. Approximate calculations using the equivalent core concept are used to clarify the relationship between the ammonia, borazine, and boron nitride spectra. It is shown that in these systems the initial Auger state (core--hole) largely localizes the bonds and lone pair on the nitrogen. The Auger spectra show that it is the sigma, ..pi.. and nonbonding orbital characters that provide the Auger fingerprint.

  7. Dynamics of coorbital satellite rings

    NASA Technical Reports Server (NTRS)

    Salo, H.; Yoder, C. F.

    1988-01-01

    The dynamical behavior of a coorbital satellite ring is studied for N = 2-9 satellites, in terms of a simplified dynamical description, in which the motion is reduced to the separation angles between satellites. The number and stability of different kinds of stationary configurations is explored, revealing that equally spaced rings are not stable against small perturbations for N not greater than 6, while for N = 2-8 there exists another, stable compact solution. Integrations of exact equations confirm these results. Moreover, the systems are found to display chaotic characteristics for a certain range of energy. The behavior can be interpreted in terms of maximum velocity curves, defining the allowed region of the motion in the phase space.

  8. Propellers in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Sremcevic, M.; Stewart, G. R.; Albers, N.; Esposito, L. W.

    2014-04-01

    Theoretical studies and simulations have demonstrated the effects caused by objects embedded in planetary rings [5, 8]. Even if the objects are too small to be directly observed, each creates a much larger gravitational imprint on the surrounding ring material. These strongly depend on the mass of the object and range from "S" like propeller-shaped structures for about 100m-sized icy bodies to the opening of circumferential gaps as in the case of the embedded moons Pan and Daphnis and their corresponding Encke and Keeler Gaps. Since the beginning of the Cassini mission many of these smaller objects (~ 100m in size) have been identified in Saturn's A ring through their propeller signature in the images [10, 7, 9, 11]. Furthermore, recent Cassini observations indicate the possible existence of objects embedded even in Saturn's B and C ring [6, 2]. In this paper we present our new results about by now classical A ring propellers and more enigmatic B ring population. Due to the presence of self-gravity wakes the analysis of propeller brightness in ISS images always bears some ambiguity [7, 9] and consequently the exact morphology of propellers is not a settled issue. In 2008 we obtained a fortunate Cassini Ultraviolet Imaging Spectrograph (UVIS) occultation of the largest A ring propeller Bleriot. Utilizing Cassini ISS images we obtain Bleriot orbit and demonstrate that UVIS Persei Rev42 occultation did cut across Bleriot about 100km downstream from the center. The occultation itself shows a prominent partial gap and higher density outer flanking wakes, while their orientation is consistent with a downstream cut. While in the UVIS occultation the partial gap is more prominent than the flanking wakes, the features mostly seen in Bleriot images are actually flanking wakes. One of the most interesting aspects of the A ring propellers are their wanderings, or longitudinal deviations from a pure circular orbit [11]. We numerically investigated the possibility of simple moon

  9. A COLLISIONAL ORIGIN FOR THE LEO RING

    SciTech Connect

    Michel-Dansac, Leo; Emsellem, Eric; Duc, Pierre-Alain; Bournaud, Frederic; Oosterloo, Tom; Morganti, Raffaella; Serra, Paolo; Ibata, Rodrigo

    2010-07-10

    Extended H I structures around galaxies are of prime importance for probing galaxy formation scenarios. The giant H I ring in the Leo group is one of the largest and most intriguing H I structures in the nearby universe. Whether it consists of primordial gas, as suggested by the apparent absence of any optical counterpart and the absence of an obvious physical connection to nearby galaxies, or of gas expelled from a galaxy in a collision is actively debated. We present deep wide field-of-view optical images of the ring region obtained with MegaCam on the CFHT. They reveal optical counterparts to several H I and UV condensations along the ring, in the g', r', and i' bands, which likely correspond to stellar associations formed within the gaseous ring. Analyzing the spectral energy distribution of one of these star-forming regions, we found it to be typical for a star-forming region in pre-enriched tidal debris. We then use simulations to test the hypothesis that the Leo ring results from a head-on collision between Leo group members NGC 3384 and M96. According to our model which is able to explain, at least qualitatively, the main observational properties of the system, the Leo ring is consistent with being a collisional ring. It is thus likely another example of extended intergalactic gas made-up of pre-enriched collisional debris.

  10. Dynamics and structure of planetary rings

    NASA Technical Reports Server (NTRS)

    French, R. G.

    1991-01-01

    Recent research efforts were directed towards sharpening the understanding of kinematical and dynamical properties of the Uranian rings, with the combination of Earth-based and Voyager observations, and in obtaining and interpreting new observations of the Saturn system from the remarkable stellar occultation of 3 Jul. 1989. Some of the highlights studied include: (1) a detailed comparison of structure and dynamics of the Uranus rings from joint analysis of high quality Earth-based data and the complete set of Voyager occultation measurements; (2) a comprehensive search for weak normal modes excited in the Uranian rings, analogous to the m = 2 and m = 0 normal modes previously identified for the delta and gamma rings; (3) an ongoing search for faint rings and ring arcs of Uranus, using both Voyager images of the rings and Earth-based and spacecraft stellar occultation data; (4) a comparison of upper stratospheric temperatures of Uranus inferred from Voyager ultraviolet occultations with results of ground-based occultation observations; and (5) observations of the 3 Jul. 1989 Saturn occultation of 28 Sgr.

  11. Optical heterodyne detection for cavity ring-down spectroscopy

    DOEpatents

    Levenson, Marc D.; Paldus, Barbara A.; Zare, Richard N.

    2000-07-25

    A cavity ring-down system for performing cavity ring-down spectroscopy (CRDS) using optical heterodyne detection of a ring-down wave E.sub.RD during a ring-down phase or a ring-up wave E.sub.RU during a ring up phase. The system sends a local oscillator wave E.sub.LO and a signal wave E.sub.SIGNAL to the cavity, preferably a ring resonator, and derives an interference signal from the combined local oscillator wave E.sub.LO and the ring-down wave E.sub.RD (or ring-up wave E.sub.RU). The local oscillator wave E.sub.LO has a first polarization and the ring-down wave E.sub.RD has a second polarization different from the first polarization. The system has a combining arrangement for combining or overlapping local oscillator wave E.sub.LO and the ring-down wave E.sub.RD at a photodetector, which receives the interference signal and generates a heterodyne current I.sub.H therefrom. Frequency and phase differences between the waves are adjustable.

  12. Effect of defocusing distance on the contaminated surface of brass ring with nanosecond laser in a 3D laser scanning system

    NASA Astrophysics Data System (ADS)

    Zhao, Mali; Liu, Tiegen; Jiang, Junfeng; Wang, Meng

    2014-08-01

    Defocusing distance plays a key role in laser cleaning result and can be either positive or negative, depending on the focus position relative to the sample surface. In this paper, we investigate the effect of the defocusing distance on the cleaning efficiency of oxidized brass surface. The oxide layer from the surface of a brass ring was processed with a three dimensional (3-D) dynamically focused laser galvanometer scanning system. The relationship between removal efficiency of the oxide layer and the defocusing distance was analyzed. The sample surface topography, element content before and after the laser cleaning were analyzed by a scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS), the surface quality after laser cleaning was analyzed by a Atomic Force Microscope (AFM), the chemical constituents of the oxide layer on the sample surface after being processed with different defocusing distances were examined by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that the ratios of Cu/O and Zn/O reach the maximum of 53.2 and 27.78 respectively when the defocusing distance is +0.5 mm. The laser pulses will lose the ability to remove the oxide layer from the substrate surface when the defocusing distance is larger than ±2 mm.

  13. Investigation of 2D photonic crystal structure based channel drop filter using quad shaped photonic crystal ring resonator for CWDM system

    NASA Astrophysics Data System (ADS)

    Chhipa, Mayur Kumar; Dusad, Lalit Kumar

    2016-05-01

    In this paper, the design & performance of two dimensional (2-D) photonic crystal structure based channel drop filter is investigated using quad shaped photonic crystal ring resonator. In this paper, Photonic Crystal (PhC) based on square lattice periodic arrays of Gallium Indium Phosphide (GaInP) rods in air structure have been investigated using Finite Difference Time Domain (FDTD) method and photonic band gap is being calculated using Plane Wave Expansion (PWE) method. The PhC designs have been optimized for telecommunication wavelength λ= 1571 nm by varying the rods lattice constant. The number of rods in Z and X directions is 21 and 20, with lattice constant 0.540 nm it illustrates that the arrangement of Gallium Indium Phosphide (GaInP) rods in the structure which gives the overall size of the device around 11.4 µm × 10.8 µm. The designed filter gives good dropping efficiency using 3.298, refractive index. The designed structure is useful for CWDM systems. This device may serve as a key component in photonic integrated circuits. The device is ultra compact with the overall size around 123 µm2.

  14. Nitration of Norcorrolatonickel(II): First Observation of a Diatropic Current in a System Comprising a Norcorrole Ring.

    PubMed

    Deng, Zhihong; Li, Xiaofang; Stępień, Marcin; Chmielewski, Piotr J

    2016-03-14

    A one-pot reaction of 5,14-bis(mesityl)-norcorrolatonickel(II) with isoamyl nitrite under mild reaction conditions resulted in the consecutive formation of 3-nitro-, 3,12-dinitro- and 3,16-dinitro-, 3,7,12-trinitro-, and 3,7,12,16-tetranitro-norcorrolatonickel(II) in 50-80% yield. The substituted macrocycles retained their antiaromatic character. The observed regioselectivity of the substitution was analyzed by comparing the relative energies of the DFT energy-optimized models of the radical or arenium cationic intermediates that can be formed upon reaction with NO2. The nitrated systems were characterized by high-resolution mass spectrometry, NMR and UV/Vis spectroscopy, X-ray diffraction analysis, cyclic voltammetry, and DFT calculations. A significant and systematic cathodic shift of the redox couples was observed to correlate with an increasing number of the NO2 group. A decrease of the LUMO energies in the tri- and tetra-nitrated products stabilizes mono- and bis-reduced complexes of these ligands. The reduction takes place on the macrocycle rather than on the metal ion leading to the consecutive formation of stable paramagnetic monoanion radicals and water-soluble diamagnetic dianions with an aromatic character, which were revealed by ESR and (1)H NMR measurements, respectively. The electronic structures of the reduced forms were analyzed by extensive TD-DFT calculations. PMID:26879706

  15. The Vulnerability of Saskatchewan Water Resource System to Multi-Year Hydrologic Droughts at North and South Saskatchewan Rivers: Fusing Paleo Tree Ring Data with Stochastic Reconstruction

    NASA Astrophysics Data System (ADS)

    Nazemi, A.; Brunet, N.; Oegema, B.

    2015-12-01

    Despite having a semi-arid cold region, the province of Saskatchewan in western Canada is home to major agricultural activities. This is due to a reliable water supply in North and South Saskatchewan rivers (hereafter NSR and SSR), initiated from the Rocky Mountain headwaters in south western Alberta. The incoming interprovincial streamflow to Saskatchewan, however, is subject to significant annual variations due to natural climate variability, climate change as well as human use and regulation. Most importantly, severe multi-year hydrologic droughts in NSR and SSR have been observed within historical and paleo records. Such long-term low flow conditions can cause vulnerability in the water supply systems, particularly if combined with an increased irrigation demand, due to global warming, crop change, meteorological drought and/or irrigation expansion. This study aims at providing a novel use of long-term annual paleo streamflow records for monthly, multi-sector drought impact assessment. By considering tree ring-based reconstructed annual streamflow records, 10-year drought sequences with 100-year return periods were obtained at NSR and SSR. The annual sequences were converted to monthly flow hydrographs using a stochastic reconstruction scheme. The water resource system was then conditioned to multiple realizations of the monthly drought sequence and simulated under various scenarios for reservoir operation and increment in irrigation demand. Simulation results show that Saskatchewan can still maintain the Saskatchewan/Manitoba apportionment requirement, even under a 10-year drought and 10 folds increment in irrigation demand. Such severe drought sequence, nonetheless, cause significant decline in Saskatchewan's hydropower production, which is currently the most profitable water sector in the province. Changes in reservoir operation, however, can considerably mitigate the adverse effects of drought and increased irrigation demand on hydropower industry

  16. Generation and development of a viscous vortex ring.

    NASA Technical Reports Server (NTRS)

    Whitehead, K. D.; Gray, R. B.

    1972-01-01

    The vorticity transport and definition of vorticity equations are derived for an axisymmetric incompressible viscous vortex ring. The coupled system is solved numerically by the Peaceman-Rachford method and the method of successive over-relaxation. Instantaneous streaklines, velocity vector fields, vorticity contours, and streamline patterns offer a detailed picture of vortex ring generation. Results compare well with experimental observations of the behavior of viscous vortex rings. The radius, trajectory, and velocity of the ring are calculated and employed to predict the propagation velocity of the vortex ring using the vortex models of Helmholtz and Hill.

  17. Cassini Radio Science Observations of Density Waves in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    McGhee, C. A.; French, R. G.; Rappaport, N. J.; Marouf, E. A.; Dawson, R.; Stack, K.

    2006-08-01

    Saturn's ring system is an elegant celestial mechanical laboratory for studying the interactions between a host of small and large moons, and the rings themselves. Resonances between the satellites and the ring particles result in spiral density waves whose detailed characteristics can be used to determine the physical properties of the rings. Over the past year, the Cassini Radio Science Team has obtained nearly a dozen exquisite radial profiles of the structure of Saturn's rings from occultations at three radio wavelengths (0.9 cm, 3 cm, and 12 cm), at sub-km resolution, after correction for the effects of diffraction. The optical depth profiles of the rings are replete with density waves produced by Mimas, Janus, Epimetheus, Prometheus, Pandora, and even smaller moons. Using wavelet decomposition as well as direct model fitting, we have determined the surface mass density and viscosity of the ring particles from weak (linear) density waves, primarily in the A ring. These are essential ingredients for dynamical models of the rings that include the effects of self-gravity and inelastic particle collisions. Future radio science occultation experiments throughout the Cassini orbital tour of Saturn will probe the rings at a range of ring opening angles, providing both additional measurements of density waves and other ring features.

  18. What's up with witch rings?

    PubMed

    Heard, Priscilla; Phillips, David

    2015-01-01

    'Witch rings' are well-known novelty rings that show a size-change illusion when rotated. We have replicated the illusion of expansion of the reflections in the rings in a variety of contexts with animations, though not as yet so successfully imitated the sense that the whole ring expands and contracts. PMID:26489222

  19. Non-Linear Dynamics of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.

    2015-10-01

    Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predatorprey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon

  20. Non-Linear Dynamics of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2015-04-01

    Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible Results of driven N-body systems by Stuart Robbins: Even unforced rings show large variations; Forcing triggers aggregation; Some limit cycles and phase lags seen, but not always as predicted by predator-prey model. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw'. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon

  1. The evolution of swirling axisymmetric vortex rings

    NASA Astrophysics Data System (ADS)

    Gargan-Shingles, C.; Rudman, M.; Ryan, K.

    2015-08-01

    Swirling vortex rings form in any turbulent flow where a swirling component is present, such as in combustion chambers or the downwash of helicopter blades. Instabilities on initially non-swirling vortex rings result in a localized swirl velocity being generated within the core. The presence of a swirl component of velocity in a vortex ring modifies the relaxation and evolution of numerical Gaussian cores in a manner that is currently unknown. The evolution of Gaussian axisymmetric vortex rings of size 0.2 < Λ < 0.5, with Gaussian swirls of magnitude 0.0 < W < 0.5, is analyzed with reference to the governing equations. A relaxation time, at which the initial Gaussian approximation has minimal influence on the subsequent evolution, has been estimated for each case. An axial vortex forms along the axis of the ring and is responsible for the growth of a shear layer that is found to form at the leading edge. The circulation based Reynolds number is set at 10 000 to encourage the growth of shear layer instabilities from within this region. Secondary vortex rings are subsequently shown to evolve from the Kelvin-Helmholtz instability for shear layers of sufficient strength and are convected around the original ring and shed from the system. It is shown that complete settling of the strain rate within the core does not occur until all sheddings have ceased. Increasing the swirl magnitude past that considered in this paper is expected to result in the original ring losing its structure before the instability can occur. The evolution is found to be qualitatively similar to that of a piston generated axisymmetric vortex ring with swirl, with both cases eventually reaching a similar quasi-steady state.

  2. DC-Powered Jumping Ring

    NASA Astrophysics Data System (ADS)

    Jeffery, Rondo N.; Amiri, Farhang

    2016-02-01

    The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant differences from the AC case. In particular, the ring does not fly off the core but rises a short distance and then falls back. If the ring jumps high enough, the rising and the falling motion of the ring does not follow simple vertical motion of a projectile. This indicates that there are additional forces on the ring in each part of its motion. Four possible stages of the motion of the ring with DC are identified, which result from the ring current changing directions during the jump in response to a changing magnetic flux through the moving ring.

  3. Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

    2010-10-01

    Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

  4. Saturn's Other Ring Current

    NASA Astrophysics Data System (ADS)

    Crary, F. J.

    2014-04-01

    Saturn's main rings orbit the planet within an atmosphere and ionosphere of water, oxygen and hydrogen, produced by meteoritic impacts on and ultraviolet photodesorbtion of the ring particles [Johnson et al., 2006; Luhmann et al., 2006; Tseng et al., 2010]. The neutral atmosphere itself has only been tentatively detected through ultraviolet fluorescents of OH [Hall et al., 1996] while the ionosphere was observed in situ by the Cassini spacecraft shortly after orbital insertion [Coates et al.,2005; Tokar et al. 2005, Waite et al. 2005]. Although the plasma flow velocity of this ionosphere is not well-constrained, but the close association with the rings suggests that its speed would be couppled to the keplarian velocity of the rings themselves. As a result, the motion of the plasma through Saturn's magnetic field would produce an induced voltage, oriented away from the planet outside synchronous orbit and towards the planet inside synchronous orbit. Such a potential could result in currents flowing across the ring plane and closeing along magnetic field lines and through Saturn's ionosphere at latitudes between 36o and 48o. Cassini observations of whistler-mode plasma wave emissions [Xin et al.,2006] centered on synchronous orbit (1.76 Rs, mapping to 41o latitude) have been interpreted as a product of field-aligned electron beams associated with such a current. This presentation will investigate the magnitude of these currents and the resulting Joule heating of the ionosphere. An important constraint is that no auroral ultraviolet emissions have been observed at the relevant latitudes. In contrast, Joule heating could affect infrared emissions from H3+. Variations in H3+ emission associated with Saturn's rings have been reported by O'Donoghue et al., 2013, and interpreted as a result of ring "rain", i.e. precipitating water group species from the rings which alter ionosphereic chemistry and H3+ densities. As noted by O'Donoghue et al., this interpretation may be

  5. Piston Ring Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kuhn, M.

    1943-01-01

    The discovery and introduction of the internal combustion engine has resulted in a very rapid development in machines utilizing the action of a piston. Design has been limited by the internal components of the engine, which has been subjected to ever increasing thermal and mechanical stresses, Of these internal engine components, the piston and piston rings are of particular importance and the momentary position of engine development is not seldom dependent upon the development of both of the components, The piston ring is a well-known component and has been used in its present shape in the steam engine of the last century, Corresponding to its importance, the piston ring has been a rich field for creative activity and it is noteworthy that in spite of this the ring has maintained its shape through the many years. From the many and complicated designs which have been suggested as a packing between piston and cylinder wall hardly one suggestion has remained which does not resemble the original design of cast iron rectangular ring.

  6. Stacked Corrugated Horn Rings

    NASA Technical Reports Server (NTRS)

    Sosnowski, John B.

    2010-01-01

    This Brief describes a method of machining and assembly when the depth of corrugations far exceeds the width and conventional machining is not practical. The horn is divided into easily machined, individual rings with shoulders to control the depth. In this specific instance, each of the corrugations is identical in profile, and only differs in diameter and outer profile. The horn is segmented into rings that are cut with an interference fit (zero clearance with all machining errors biased toward contact). The interference faces can be cut with a reverse taper to increase the holding strength of the joint. The taper is a compromise between the interference fit and the clearance of the two faces during assembly. Each internal ring is dipped in liquid nitrogen, then nested in the previous, larger ring. The ring is rotated in the nest until the temperature of the two parts equalizes and the pieces lock together. The resulting assay is stable, strong, and has an internal finish that cannot be achieved through other methods.

  7. Further explorations of cosmogonic shadow effects in the Saturnian rings

    NASA Technical Reports Server (NTRS)

    Alfven, H.; Axnaes, I.; Brenning, N.; Lindqvist, P. A.

    1985-01-01

    The mass distribution in the Saturnian ring system is compared with predictions from the cosmogonic theory of Alfven and Arrhenius (1975) in which matter in the rings was once a magnetized plasma, with gravitation balanced by centrifugal force and by the magnetic field. As the plasma is neutralized, the magnetic force disappears and the matter can be shown to fall in to a distance 2/3 of the original. This supports the cosmogonic shadow effect, also demonstrated for the astroidal belt and in the large scale structure of the Saturnian ring system. The relevance of the comogonic shadow effect for parts of the finer structures of the Saturnian ring system is investigated. It is shown that many structures of the present ring system can be understood as shadows and antishadows of cosmogonic origin. These appear in the form of double rings centered around a position a factor 0.64 (slightly 2/3) closer to Saturn than the causing feature.

  8. Rheology of Ring Polymer Melts: From Linear Contaminants to Ring-Linear Blends

    NASA Astrophysics Data System (ADS)

    Halverson, Jonathan D.; Grest, Gary S.; Grosberg, Alexander Y.; Kremer, Kurt

    2012-01-01

    Ring polymers remain a challenge to our understanding of polymer dynamics. Experiments are difficult to interpret because of the uncertainty in the purity and dispersity of the sample. Using both equilibrium and nonequilibrium molecular dynamics simulations we have investigated the structure, dynamics, and rheology of perfectly controlled ring-linear polymer blends of chains of up to about 14 entanglements per chain, comparable to experimental systems. Linear contaminants increase the zero-shear viscosity of a ring polymer melt by about 10% around one-fifth of their overlap concentration. For equal concentrations of linear and ring polymers, the blend viscosity is about twice that of the pure linear melt. The diffusion coefficient of the rings decreases dramatically, while the linear polymers are mostly unaffected. Our results are supported by a primitive path analysis.

  9. GRISM Spectophotometry of the Uranus Ring

    NASA Astrophysics Data System (ADS)

    Smith, Bradford

    1997-07-01

    Details of the near-infrared spectral reflectance of the Uranus rings are poorly known, because of problems associated with the scattered light from the planet. Grism spectroscopy of the brightest part of the Epsilon ring will be made with the planet just outside the field of view. To minimize the glare from Uranus, the observations should made when the widest part of the Epsilon ring is at a position angle of approximately 174 degrees. This is one in a series of observations designed to intercompare the near-infrared spectral reflectivity of dark objects in the solar system. Some record of processes that occurred within the Uranus subnebula may be left on the surfaces of the ring particles or the surface coatings of the associated dark inner satellites.

  10. Resonance splitting in gyrotropic ring resonators.

    PubMed

    Jalas, Dirk; Petrov, Alexander; Krause, Michael; Hampe, Jan; Eich, Manfred

    2010-10-15

    We present the theoretical concept of an optical isolator based on resonance splitting in a silicon ring resonator covered with a magneto-optical polymer cladding. For this task, a perturbation method is derived for the modes in the cylindrical coordinate system. A polymer magneto-optical cladding causing a 0.01 amplitude of the off-diagonal element of the dielectric tensor is assumed. It is shown that the derived resonance splitting of the clockwise and counterclockwise modes increases for smaller ring radii. For the ring with a radius of approximately 1.5μm, a 29GHz splitting is demonstrated. An integrated optical isolator with a 10μm geometrical footprint is proposed based on a critically coupled ring resonator. PMID:20967092

  11. Low thermal expansion seal ring support

    DOEpatents

    Dewis, David W.; Glezer, Boris

    2000-01-01

    Today, the trend is to increase the temperature of operation of gas turbine engines. To cool the components with compressor discharge air, robs air which could otherwise be used for combustion and creates a less efficient gas turbine engine. The present low thermal expansion sealing ring support system reduces the quantity of cooling air required while maintaining life and longevity of the components. Additionally, the low thermal expansion sealing ring reduces the clearance "C","C'" demanded between the interface between the sealing surface and the tip of the plurality of turbine blades. The sealing ring is supported by a plurality of support members in a manner in which the sealing ring and the plurality of support members independently expand and contract relative to each other and to other gas turbine engine components.

  12. Rings dominate western Gulf

    NASA Astrophysics Data System (ADS)

    Vidal L., Francisco V.; Vidal L., Victor M. V.; Molero, José María Pérez

    Surface and deep circulation of the central and western Gulf of Mexico is controlled by interactions of rings of water pinched from the gulf's Loop Current. The discovery was made by Mexican oceanographers who are preparing a full-color, 8-volume oceanographic atlas of the gulf.Anticyclonic warm-core rings pinch off the Loop Current at a rate of about one to two per year, the scientists of the Grupo de Estudios Oceanográficos of the Instituto de Investigaciones Eléctricas (GEO-IIE) found. The rings migrate west until they collide with the continental shelf break of the western gulf, almost always between 22° and 23°N latitude. On their westward travel they transfer angular momentum and vorticity to the surrounding water, generating cyclonic circulations and vortex pairs that completely dominate the entire surface and deep circulation of the central and western gulf.

  13. Deployable Fresnel Rings

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

    2014-01-01

    Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the

  14. Degradation Characteristics of O-rings on Highly Aged GIS

    NASA Astrophysics Data System (ADS)

    Minagawa, Tadao; Nagao, Eiichi; Tsuchie, Ei; Yonezawa, Hiroshi; Takayama, Daisuke; Yamakawa, Yutaka

    Owing to increasing number of highly aged GIS, the investigation of the remaining lifetimes of those systems are becoming more important. Because a lot of O-rings are used in GIS, the study of degradation mechanism and lifetime estimation method of O-ring is essential. In this paper, the information about O-ring degradation mechanism is described, and the statistical method for estimating the remaining lifetime of O-ring is proposed. The degradation of O-ring is mainly subject to chemical reactions triggered by oxygen. Because there are many factors influencing those chemical reactions, the dispersion of degradation rates of O-rings in GIS is very large. Consequently the statistical analysis is one of the effective techniques for lifetime estimation of O-rings in GIS.

  15. Sliding-Ring Catenanes.

    PubMed

    Fernando, Isurika R; Frasconi, Marco; Wu, Yilei; Liu, Wei-Guang; Wasielewski, Michael R; Goddard, William A; Stoddart, J Fraser

    2016-08-17

    Template-directed protocols provide a routine approach to the synthesis of mechanically interlocked molecules (MIMs), in which the mechanical bonds are stabilized by a wide variety of weak interactions. In this Article, we describe a strategy for the preparation of neutral [2]catenanes with sliding interlocked electron-rich rings, starting from two degenerate donor-acceptor [2]catenanes, consisting of a tetracationic cyclobis(paraquat-p-phenylene) cyclophane (CBPQT(4+)) and crown ethers containing either (i) hydroquinone (HQ) or (ii) 1,5-dioxynaphthalene (DNP) recognition units and carrying out four-electron reductions of the cyclophane components to their neutral forms. The donor-acceptor interactions between the CBPQT(4+) ring and both HQ and DNP units present in the crown ethers that stabilize the [2]catenanes are weakened upon reduction of the cyclophane components to their radical cationic states and are all but absent in their fully reduced states. Characterization in solution performed by UV-vis, EPR, and NMR spectroscopic probes reveals that changes in the redox properties of the [2]catenanes result in a substantial decrease of the energy barriers for the circumrotation and pirouetting motions of the interlocked rings, which glide freely through one another in the neutral states. The solid-state structures of the fully reduced catenanes reveal profound changes in the relative dispositions of the interlocked rings, with the glycol chains of the crown ethers residing in the cavities of the neutral CBPQT(0) rings. Quantum mechanical investigations of the energy levels associated with the four different oxidation states of the catenanes support this interpretation. Catenanes and rotaxanes with sliding rings are expected to display unique properties. PMID:27398609

  16. GUARD RING SEMICONDUCTOR JUNCTION

    DOEpatents

    Goulding, F.S.; Hansen, W.L.

    1963-12-01

    A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

  17. Ringed Accretion Disks: Instabilities

    NASA Astrophysics Data System (ADS)

    Pugliese, D.; Stuchlík, Z.

    2016-04-01

    We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.

  18. Unidirectional ring lasers

    DOEpatents

    Hohimer, J.P.; Craft, D.C.

    1994-09-20

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity is disclosed. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction. 21 figs.

  19. Unidirectional ring lasers

    DOEpatents

    Hohimer, John P.; Craft, David C.

    1994-01-01

    Unidirectional ring lasers formed by integrating nonreciprocal optical elements into the resonant ring cavity. These optical elements either attenuate light traveling in a nonpreferred direction or amplify light traveling in a preferred direction. In one preferred embodiment the resonant cavity takes the form of a circle with an S-shaped crossover waveguide connected to two points on the interior of the cavity such that light traveling in a nonpreferred direction is diverted from the cavity into the crossover waveguide and reinjected out of the other end of the crossover waveguide into the cavity as light traveling in the preferred direction.

  20. The covariant chiral ring

    NASA Astrophysics Data System (ADS)

    Bourget, Antoine; Troost, Jan

    2016-03-01

    We construct a covariant generating function for the spectrum of chiral primaries of symmetric orbifold conformal field theories with N = (4 , 4) supersymmetry in two dimensions. For seed target spaces K3 and T 4, the generating functions capture the SO(21) and SO(5) representation theoretic content of the chiral ring respectively. Via string dualities, we relate the transformation properties of the chiral ring under these isometries of the moduli space to the Lorentz covariance of perturbative string partition functions in flat space.